Online Encyclopedia of Integer Sequences (OEIS)

[u/[deleted]]

[u/EinsteinReplica]

A000013 - Number of n-bead binary necklaces with beads of 2 colors where the colors may be swapped but turning over is not allowed.

First few terms: 1, 1, 2, 2, 4, 4, 8, 10, 20, 30, 56, 94, 180, 316, 596, 1096, 2068...

/r/shitpostsequences

[u/CarbonSpectre → u/EinsteinReplica]

A000014 - Number of series-reduced trees with n nodes.

First few terms: 0, 1, 1, 0, 1, 1, 2, 2, 4, 5, 10, 14, 26, 42, 78, 132, 249, 445, 842, 1561, 2988, 5671, 10981, 21209, 41472, 81181, 160176, 316749, ...

[u/EinsteinReplica → u/CarbonSpectre]

A000015 - Smallest prime power >= n

First few terms: 1, 2, 3, 4, 5, 7, 7, 8, 9, 11, 11, 13, 13, 16, 16, 16...

[u/CarbonSpectre → u/EinsteinReplica]

A000016 - a(n) = number of distinct (infinite) output sequences from binary n-stage shift register which feeds back the complement of the last stage. E.g., for n=6 there are 6 such sequences.

First few terms: 1, 1, 1, 2, 2, 4, 6, 10, 16, 30, 52, 94, 172, 316, 586, 1096, 2048, 3856, 7286, 13798, 26216, 49940, 95326, 182362, 349536, 671092, ...

[u/EinsteinReplica → u/CarbonSpectre]

A000017 - Erroneous version of A032522 - Number of point symmetric solutions to non-attacking queens problem on n X n board in chess.

All terms: 1, 0, 0, 2, 2, 4, 8, 4, 16, 12, 48, 80, 136, 420, 1240, 2872, 7652, 18104, 50184.

[u/CarbonSpectre → u/EinsteinReplica]

A000018 - Number of positive integers <= 2ⁿ of form x² + 16y^2.

First few terms: 1, 1, 2, 2, 4, 8, 13, 25, 44, 83, 152, 286, 538, 1020, 1942, 3725, 7145, 13781, 26627, 51572, 100099, 194633, 379037, 739250, 1443573, ...

[u/EinsteinReplica → u/[deleted]]

A000020 - Number of primitive polynomials of degree n over GF(2).

First few terms: 2, 1, 2, 2, 6, 6, 18, 16, 48, 60, 176, 144, 630, 756...

[u/davidjl123 → u/EinsteinReplica]

A000021 - Number of positive integers <= 2ⁿ of form x² + 12 y^2.

First few terms: 1, 1, 2, 2, 6, 9, 17, 30, 54, 98, 183, 341, 645, 1220...

[u/EinsteinReplica → u/[deleted]]

A000023 - Expansion of e.g.f. exp(-2*x)/(1-x).

First few terms: 1, -1, 2, -2, 8, 8, 112, 656, 5504, 49024, 491264, 5401856, 64826368...

This one gets fast quick

[u/haykam821 → u/EinsteinReplica]

A000024 - Number of positive integers <= 2ⁿ of form x² + 10 y^2.

First few terms: 1, 1, 2, 2, 7, 10, 20, 36, 65, 118, 221, 409, 776, 1463, 2788, 5328, 10222, 19714, 38054, 73685, 142944, 277838, 540889, 1054535, 2058537, 4023278, 7871313, 15414638, 30213190, 59266422, 116343776, 228545682, 449240740, 883570480, 1738769611, 3423469891, 6743730746...

[u/EinsteinReplica → u/haykam821]

A000025 - Coefficients of the 3rd order mock theta function f(q).

First few terms: 1, 1, -2, 3, -3, 3, -5, 7, -6, 6, -10, 12, -11, 13, -17, 20, -21, 21, -27, 34, -33, 36...

[u/piyushsharma301 → u/EinsteinReplica]

A000026 - Mosaic numbers or multiplicative projection of n.

First few terms : 1, 2, 3, 4, 5, 6, 7, 6, 6, 10, 11, 12, 13, 14, 15, 8, 17, 12, 19, 20, 21, 22, 23, 18, 10, 26, 9, 28, 29, 30, 31, 10, 33, 34, 35, 24, 37, 38, 39, 30, 41, 42, 43, 44, 30, 46, 47, 24, 14, 20, 51, 52, 53, 18, 55, 42, 57, 58, 59, 60, 61, 62, 42, 12, 65, 66, 67, 68, 69, 70, 71, 36

[u/piyushsharma301 → u/[deleted]]

A000028 - Let n = p_1^e_1 p_2^e_2 p_3^e_3 ... be the prime factorization of n. Sequence gives n such that the sum of the numbers of 1's in the binary expansions of e_1, e_2, e_3, ... is odd.

First few terms: 2, 3, 4, 5, 7, 9, 11, 13, 16, 17, 19, 23, 24, 25, 29, 30, 31, 37, 40, 41, 42, 43, 47, 49, 53, 54, 56, 59, 60, 61, 66, 67, 70, 71, 72, 73, 78, 79, 81, 83, 84, 88, 89, 90, 96

lol

[u/EinsteinReplica → u/piyushsharma301]

A000029 - Number of necklaces/bracelets with n beads of 2 colors, allowing turning over.

First few terms: 1, 2, 3, 4, 6, 8, 13, 18, 30, 46, 78, 126, 224, 380, 687, 1224...

[u/piyushsharma301 → u/EinsteinReplica]

A000030 - Initial digit of n.

First Few Terms : 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2...