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 1-3 of 3 results.

A306022 Stirling transform of partitions numbers (A000041).

Original entry on oeis.org

1, 1, 3, 10, 38, 163, 774, 4006, 22376, 133951, 854402, 5775948, 41190317, 308651432, 2422315371, 19856073597, 169596622997, 1506139073454, 13879704561038, 132488897335228, 1307829322689944, 13330635710335512, 140118664473276174, 1516899115597189064
Offset: 0

Views

Author

Vaclav Kotesovec, Jun 17 2018

Keywords

Crossrefs

Programs

  • Maple
    a:= n-> add(combinat[numbpart](j)*Stirling2(n, j), j=0..n):
    seq(a(n), n=0..30);  # Alois P. Heinz, Jun 17 2018
  • Mathematica
    Table[Sum[StirlingS2[n, k]*PartitionsP[k], {k, 0, n}], {n, 0, 25}]
  • PARI
    a(n) = sum(k=0, n, stirling(n, k, 2)*numbpart(k)); \\ Michel Marcus, Jun 17 2018

Formula

a(n) = Sum_{k=0..n} Stirling2(n,k)*A000041(k).

A298905 Expansion of e.g.f. Product_{k>=1} (1 + log(1 + x)^k).

Original entry on oeis.org

1, 1, 1, 8, -8, 224, -712, 9120, -53496, 980088, -14394648, 264140832, -4113747024, 59028225840, -545558201424, -4191307074432, 450100910950272, -17302659472138752, 530508727766191104, -14790496500550616832, 408513443917280375808, -12274212131738107257600
Offset: 0

Views

Author

Ilya Gutkovskiy, Jun 18 2018

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1, add(b(n-j)*add(
         `if`(d::odd, d, 0), d=numtheory[divisors](j)), j=1..n)/n)
        end:
    a:= n-> add(Stirling1(n, j)*b(j)*j!, j=0..n):
    seq(a(n), n=0..23);  # Alois P. Heinz, Jun 18 2018
  • Mathematica
    nmax = 21; CoefficientList[Series[Product[(1 + Log[1 + x]^k), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
    nmax = 21; CoefficientList[Series[Exp[Sum[(-1)^(k + 1) Log[1 + x]^k/(k (1 - Log[1 + x]^k)), {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
    Table[Sum[StirlingS1[n, k] PartitionsQ[k] k!, {k, 0, n}], {n, 0, 21}]

Formula

E.g.f.: exp(Sum_{k>=1} (-1)^(k+1)*log(1 + x)^k/(k*(1 - log(1 + x)^k))).
a(n) = Sum_{k=0..n} Stirling1(n,k)*A000009(k)*k!.

A316146 a(n) = Sum_{k=0..n} Stirling2(n,k) * A000009(k) * k^k.

Original entry on oeis.org

1, 5, 67, 865, 15906, 365514, 9545026, 276368635, 9188742238, 343857717788, 13998751394662, 618098575755637, 29469995998980356, 1510585321262760900, 83100039017148288635, 4873627957977247842223, 302388593396139280682588, 19804146883678522219587314
Offset: 1

Views

Author

Vaclav Kotesovec, Jun 25 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[StirlingS2[n, k] * PartitionsQ[k] * k^k, {k, 1, n}], {n, 1, 20}]

Formula

Limit_{n -> infinity} (a(n)/n!)^(1/n) = 1/(log(1+ exp(1)) - 1) = 3.1922192845297391106277924019427161296056687330974482534324... - Vaclav Kotesovec, Nov 21 2021
log(A316145(n) / a(n)) ~ (sqrt(2) - 1) * Pi * sqrt(n) / sqrt(3*(1 + exp(1)) * log(1 + exp(-1))). - Vaclav Kotesovec, Nov 22 2021
Showing 1-3 of 3 results.