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.

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A305560 Expansion of Sum_{k>=0} binomial(k,floor(k/2))*x^k/Product_{j=1..k} (1 - j*x).

Original entry on oeis.org

1, 1, 3, 10, 39, 176, 893, 4985, 30229, 197452, 1379655, 10250087, 80558195, 666916238, 5795111845, 52691973136, 499969246647, 4938724595994, 50679201983653, 539209298355565, 5938139329609621, 67582179415195986, 793755139140445707, 9608367683839952732, 119730171975510540577
Offset: 0

Views

Author

Ilya Gutkovskiy, Jun 21 2018

Keywords

Comments

Stirling transform of A001405.

Crossrefs

Programs

  • Maple
    a:= n-> add(binomial(j, floor(j/2))*Stirling2(n, j), j=0..n):
    seq(a(n), n=0..30);  # Alois P. Heinz, Jun 21 2018
  • Mathematica
    nmax = 24; CoefficientList[Series[Sum[Binomial[k, Floor[k/2]] x^k/Product[1 - j x, {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]
    nmax = 24; CoefficientList[Series[BesselI[0, 2 (Exp[x] - 1)] + BesselI[1, 2 (Exp[x] - 1)], {x, 0, nmax}], x] Range[0, nmax]!
    Table[Sum[StirlingS2[n, k] Binomial[k, Floor[k/2]], {k, 0, n}], {n, 0, 24}]

Formula

E.g.f.: BesselI(0,2*(exp(x) - 1)) + BesselI(1,2*(exp(x) - 1)).
a(n) = Sum_{k=0..n} Stirling2(n,k)*binomial(k,floor(k/2)).

A317310 Expansion of e.g.f. (1 + x)^2*BesselI(0,2*log(1 + x)).

Original entry on oeis.org

1, 2, 4, 6, 4, 0, -2, 14, -100, 792, -6996, 68508, -737882, 8676200, -110627142, 1520662410, -22418697948, 352885526856, -5907074659016, 104782694989616, -1963418893492364, 38753471698684512, -803656781974363412, 17469671114170029708, -397223288562294817330, 9429329994809282773300
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 22 2019

Keywords

Crossrefs

Programs

  • Maple
    a:=series((1 + x)^2*BesselI(0,2*log(1 + x)), x=0, 26): seq(n!*coeff(a, x, n), n=0..25); # Paolo P. Lava, Mar 26 2019
  • Mathematica
    nmax = 25; CoefficientList[Series[(1 + x)^2 BesselI[0, 2 Log[1 + x]], {x, 0, nmax}], x] Range[0, nmax]!
    Table[Sum[StirlingS1[n, k] Binomial[2 k, k], {k, 0, n}], {n, 0, 25}]
  • PARI
    my(x='x + O('x^30)); Vec(serlaplace((1 + x)^2*besseli(0,2*log(1 + x)))) \\ Michel Marcus, Mar 27 2019

Formula

a(n) = Sum_{k=0..n} Stirling1(n,k)*A000984(k).
Showing 1-2 of 2 results.