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.

A362205 Expansion of e.g.f. exp(x/(1-3*x)^(1/3)).

Original entry on oeis.org

1, 1, 3, 19, 185, 2401, 38731, 745123, 16630769, 422157025, 12005107091, 377957000851, 13048046175913, 490052749100929, 19890724260375515, 867582126490694371, 40467070835396193761, 2009901604798183428673, 105901641663222888913699
Offset: 0

Views

Author

Seiichi Manyama, Apr 11 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(x/(1-3*x)^(1/3))))

Formula

a(n) = n! * Sum_{k=0..n} (-3)^k * binomial(-(n-k)/3,k)/(n-k)! = n! * Sum_{k=0..n} 3^(n-k) * binomial(n-2*k/3-1,n-k)/k!.

A382643 Expansion of e.g.f. exp( x/(1-3*x)^(4/3) ).

Original entry on oeis.org

1, 1, 9, 109, 1697, 32401, 733081, 19167709, 568351169, 18833921857, 689436160361, 27616959669421, 1201138514382049, 56349982190989969, 2835621797645900537, 152321976433436677981, 8697876904012444443521, 526015632425455532060929, 33581536744768011688139209
Offset: 0

Views

Author

Seiichi Manyama, Apr 03 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*sum(k=0, n, 3^(n-k)*binomial(n+k/3-1, n-k)/k!);

Formula

a(n) = n! * Sum_{k=0..n} 3^(n-k) * binomial(n+k/3-1,n-k)/k!.
a(n) ~ 2^(3/7) * 3^(n + 1/14) * n^(n - 3/14) * exp(-2^(-2/7)*3^(-12/7)*n^(1/7) + 7*2^(-8/7)*3^(-6/7)*n^(4/7) - n) / sqrt(7). - Vaclav Kotesovec, Apr 17 2025

A382652 Expansion of e.g.f. exp( x/(1-3*x)^(5/3) ).

Original entry on oeis.org

1, 1, 11, 151, 2601, 54401, 1341571, 38115351, 1225252561, 43935295681, 1737463744251, 75075845199191, 3517448555579641, 177538212306653121, 9600694935999031411, 553606933661659742551, 33899768045328467219361, 2196417680635853609034881, 150094038119761737476004331
Offset: 0

Views

Author

Seiichi Manyama, Apr 03 2025

Keywords

Crossrefs

Programs

  • Maple
    exp(x/(1-3*x)^(5/3)) ;
    taylor(%,x=0,60) ;
    L := gfun[seriestolist](%) ;
    seq( op(i,L)*(i-1)!,i=1..nops(L)) ; # R. J. Mathar, Apr 08 2025
  • PARI
    a(n) = n!*sum(k=0, n, 3^(n-k)*binomial(n+2*k/3-1, n-k)/k!);

Formula

a(n) = n! * Sum_{k=0..n} 3^(n-k) * binomial(n+2*k/3-1,n-k)/k!.
a(n) ~ 2^(-3/2) * 5^(3/16) * 3^(n + 1/8) * n^(n - 3/16) * exp(-3^(-3/2)*5^(-1/4)*n^(1/4)/2 + 8*5^(-5/8)*3^(-3/4)*n^(5/8) - n). - Vaclav Kotesovec, Apr 19 2025
Showing 1-3 of 3 results.