cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-6 of 6 results.

A025157 Number of partitions of n with distinct parts p(i) such that if i != j, then |p(i) - p(j)| >= 3.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 6, 7, 8, 10, 11, 13, 15, 17, 19, 22, 25, 28, 32, 36, 41, 46, 52, 58, 66, 73, 82, 91, 102, 113, 126, 139, 155, 171, 190, 209, 232, 255, 282, 310, 342, 375, 413, 452, 497, 544, 596, 651, 713, 778, 850, 927, 1011, 1101, 1200, 1305, 1420, 1544, 1677, 1821, 1977, 2144, 2324, 2519, 2728
Offset: 0

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Comments

Also number of partitions of n into distinct parts in which the smallest part is greater than or equal to number of parts. - Vladeta Jovovic, Aug 06 2004

Examples

			a(12) = 6 because we have 12 = 11+1 = 10+2 = 9+3 = 8+4 = 7+4+1.
		

Crossrefs

Column k=3 of A194543.

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(n>
          ceil(i*(i+3)/6), 0, b(n, i-1)+b(n-i, min(n-i, i-3))))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..70);  # Alois P. Heinz, Jan 26 2022
  • Mathematica
    nn=50; CoefficientList[Series[Sum[x^(j(3j-1)/2)Product[1/(1-x^i), {i, 1, j}], {j, 0, nn}], {x, 0, nn}], x] (* Geoffrey Critzer, Jul 21 2013 *)
  • PARI
    my(N=99, x='x+O('x^N)); Vec(sum(k=0, N, x^(k*(3*k-1)/2)/prod(j=1, k, 1-x^j))) \\ Seiichi Manyama, Jan 13 2022

Formula

G.f.: sum(i>=1, x^(3*A000217(i)-2*i)/product(j=1..i, 1-x^j)). - Jon Perry, Jul 20 2004
G.f.: sum(n>=0, x^(n*(3*n-1)/2)/prod(k=1..n,1-x^k)). - Joerg Arndt, Jan 29 2011
a(n) ~ c^(1/4) * exp(2*sqrt(c*n)) / (2*n^(3/4)*r*sqrt(Pi*(1+3*r^2))), where r = A263719 = ((9+sqrt(93))/2)^(1/3)/3^(2/3) - (2/(3*(9+sqrt(93))))^(1/3) = 0.682327803828019327369483739711048256891188581898... is the root of the equation r^3 + r = 1 and c = 3*(log(r))^2/2 + polylog(2, 1-r) = 0.566433354765746647188050807325058683443823543741343518... . - Vaclav Kotesovec, Jan 02 2016

Extensions

Prepended a(0)=1, Joerg Arndt, Jul 21 2013

A025162 Number of partitions of n with distinct parts p(i) such that if i != j, then |p(i) - p(j)| >= 8.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 29, 32, 35, 38, 41, 45, 48, 52, 56, 60, 64, 69, 73, 78, 83, 89, 94, 101, 107, 115, 122, 131, 139, 150, 159, 171, 182, 196, 208, 224, 238, 256, 272, 292, 310
Offset: 1

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Crossrefs

Column k=8 of A194543.

Formula

G.f.: Sum(x^(4*k^2-3*k)/Product(1-x^i, i=1..k), k=1..infinity). - Vladeta Jovovic, Aug 12 2004

Extensions

More terms from Naohiro Nomoto, Feb 27 2002

A025158 Number of partitions of n with distinct parts p(i) such that if i != j, then |p(i) - p(j)| >= 4.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 7, 8, 9, 11, 12, 14, 16, 18, 20, 23, 25, 28, 31, 35, 38, 43, 47, 53, 58, 65, 71, 80, 87, 97, 106, 118, 128, 142, 154, 170, 185, 203, 220, 242, 262, 287, 311, 340, 368, 402, 435, 474, 513, 558, 603, 656, 708, 768, 829, 898, 968, 1048
Offset: 1

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Comments

Also number of partitions of n such that if k is the largest part, then each 1,2,...,k-1 occur at least 4 times. Example: a(8)=3 because we have [2,2,1,1,1,1], [2,1,1,1,1,1,1] and [1,1,1,1,1,1,1,1]. - Emeric Deutsch, Apr 17 2006

Examples

			a(8) = 3 because we have [8], [7,1] and [6,2].
		

Crossrefs

Column k=4 of A194543.

Programs

  • Maple
    g:=sum(x^(2*k^2-k)/product(1-x^j,j=1..k),k=1..7): gser:=series(g,x=0,70): seq(coeff(gser,x,n),n=1..66); # Emeric Deutsch, Apr 17 2006
  • Mathematica
    nmax = 100; Rest[CoefficientList[1 + Series[Sum[x^(j*(2*j - 1))/Product[1 - x^i, {i, 1, j}], {j, 1, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Jan 02 2016 *)

Formula

G.f.: Sum(x^(2*k^2-k)/Product(1-x^i, i=1..k), k=1..infinity). - Vladeta Jovovic, Aug 12 2004
a(n) ~ c^(1/4) * exp(2*sqrt(c*n)) / (2*n^(3/4)*sqrt(Pi*r^3*(1+4*r^3))), where r = 0.72449195900051561158837228218703656578649448135001101727... is the root of the equation r^4 + r = 1 and c = 2*log(r)^2 + polylog(2, 1-r) = 0.50498141294472195442598916817438524920370382784609501495065... . - Vaclav Kotesovec, Jan 02 2016

Extensions

More terms from Vladeta Jovovic, Aug 12 2004

A025159 Number of partitions of n with distinct parts p(i) such that if i != j, then |p(i) - p(j)| >= 5.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 8, 9, 10, 12, 13, 15, 17, 19, 21, 24, 26, 29, 32, 35, 38, 42, 46, 50, 55, 60, 66, 72, 79, 86, 95, 103, 113, 123, 135, 146, 160, 173, 189, 204, 222, 239, 260, 280, 303, 326, 353, 379, 410, 440, 475, 510, 550, 590, 636, 682
Offset: 1

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Crossrefs

Column k=5 of A194543.

Formula

G.f.: Sum(x^(5/2*k^2-3/2*k)/Product(1-x^i, i=1..k), k=1..infinity). - Vladeta Jovovic, Aug 12 2004
a(n) ~ c^(1/4) * r * exp(2*sqrt(c*n)) / (2*sqrt(Pi*(1-r)*(5-4*r)) * n^(3/4)), where r = 0.754877666246692760049508896358528691894606617772793143989... is the root of the equation r^5 + r = 1 and c = 5*log(r)^2/2 + polylog(2, 1-r) = 0.45973143655369174108251201834952526825516678... . - Vaclav Kotesovec, Jan 02 2016

Extensions

More terms from Vladeta Jovovic, Aug 12 2004

A025160 Number of partitions of n with distinct parts p(i) such that if i != j, then |p(i) - p(j)| >= 6.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 9, 10, 11, 13, 14, 16, 18, 20, 22, 25, 27, 30, 33, 36, 39, 43, 46, 50, 54, 59, 63, 69, 74, 81, 87, 95, 102, 112, 120, 131, 141, 154, 165, 180, 193, 210, 225, 244, 261, 283, 302, 326, 348, 375, 400, 430, 458, 492
Offset: 1

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Crossrefs

Column k=6 of A194543.

Formula

G.f.: Sum(x^(3*k^2-2*k)/Product(1-x^i, i=1..k), k=1..infinity). - Vladeta Jovovic, Aug 12 2004

Extensions

More terms from Vladeta Jovovic, Aug 12 2004

A025161 Number of partitions of n with distinct parts p(i) such that if i != j, then |p(i) - p(j)| >= 7.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 10, 11, 12, 14, 15, 17, 19, 21, 23, 26, 28, 31, 34, 37, 40, 44, 47, 51, 55, 59, 63, 68, 73, 78, 84, 90, 97, 104, 112, 120, 130, 139, 150, 161, 174, 186, 201, 215, 232, 248, 267, 285, 307, 327, 351, 374, 401
Offset: 1

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Crossrefs

Column k=7 of A194543.

Formula

G.f.: Sum(x^(7/2*k^2-5/2*k)/Product(1-x^i, i=1..k), k=1..infinity). - Vladeta Jovovic, Aug 12 2004

Extensions

More terms from Naohiro Nomoto, Feb 27 2002
Showing 1-6 of 6 results.