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 1-4 of 4 results.

A377832 Expansion of e.g.f. (1/x) * Series_Reversion( x * (1 - x)^2 * exp(-x) ).

Original entry on oeis.org

1, 3, 29, 508, 13137, 452616, 19549021, 1016932512, 61940154177, 4325943203200, 340900244374461, 29927648769380352, 2896829645184711121, 306522175683831195648, 35201889560564096132925, 4360880891670519541927936, 579686447990401730151243009, 82304944815106131595482267648
Offset: 0

Views

Author

Seiichi Manyama, Nov 09 2024

Keywords

Crossrefs

Programs

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

Formula

E.g.f. A(x) satisfies A(x) = exp(x * A(x))/(1 - x*A(x))^2.
a(n) = n! * Sum_{k=0..n} (n+1)^(k-1) * binomial(3*n-k+1,n-k)/k!.
a(n) ~ (1 + sqrt(3))^(4*n + 5/2) * n^(n-1) / (3^(1/4) * 2^(3*n + 5/2) * exp((sqrt(3) - 1)*n - 2 + sqrt(3))). - Vaclav Kotesovec, Nov 09 2024

A377811 E.g.f. satisfies A(x) = exp(x * A(x)) / (1 - x)^3.

Original entry on oeis.org

1, 4, 27, 283, 4217, 82971, 2041855, 60475885, 2096566449, 83324680435, 3736041351311, 186594364199277, 10274269171279657, 618386703880855339, 40393224245061185919, 2846030947359659421901, 215160957844217080056161, 17373449685399138641312739, 1492298627191467511376377999
Offset: 0

Views

Author

Seiichi Manyama, Nov 08 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(-lambertw(-x/(1-x)^3))/(1-x)^3))
    
  • PARI
    a(n) = n!*sum(k=0, n, (k+1)^(k-1)*binomial(n+2*k+2, n-k)/k!);

Formula

E.g.f.: exp( -LambertW(-x/(1-x)^3) )/(1-x)^3.
E.g.f.: -LambertW(-x/(1-x)^3)/x.
a(n) = n! * Sum_{k=0..n} (k+1)^(k-1) * binomial(n+2*k+2,n-k)/k!.

A377827 E.g.f. satisfies A(x) = (1 + x)^2 * exp(x * A(x)).

Original entry on oeis.org

1, 3, 13, 106, 1273, 20226, 402589, 9637902, 269967793, 8666441650, 313793596981, 12653878751526, 562489374836041, 27328756018660266, 1440892788988703821, 81940739770677315646, 4999648556871348611425, 325806859913842861709922, 22584652022005415601772645
Offset: 0

Views

Author

Seiichi Manyama, Nov 09 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*sum(k=0, n, (k+1)^(k-1)*binomial(2*k+2, n-k)/k!);

Formula

E.g.f.: (1+x)^2 * exp( -LambertW(-x*(1+x)^2) ).
E.g.f.: -LambertW(-x*(1+x)^2)/x.
a(n) = n! * Sum_{k=0..n} (k+1)^(k-1) * binomial(2*k+2,n-k)/k!.
a(n) ~ sqrt(1 + 3*r) * n^(n-1) / (exp(n - 1/4) * r^(n + 3/4)), where r = 0.2394629861788505554394435808448... is root of the equation r*(1+r)^2 = exp(-1). - Vaclav Kotesovec, Nov 09 2024

A377595 E.g.f. satisfies A(x) = exp( x * A(x) / (1-x) ) / (1-x).

Original entry on oeis.org

1, 2, 11, 103, 1377, 24101, 523813, 13636463, 414246017, 14396807161, 563682761541, 24559156435595, 1178780540094193, 61810491468265541, 3515914378433242997, 215647516162031069191, 14187967957218808201089, 996767406049512569338481, 74478502236949781909301253
Offset: 0

Views

Author

Seiichi Manyama, Nov 14 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(-lambertw(-x/(1-x)^2))/(1-x)))
    
  • PARI
    a(n) = n!*sum(k=0, n, (k+1)^(k-1)*binomial(n+k, n-k)/k!);

Formula

E.g.f.: exp( -LambertW(-x/(1-x)^2) )/(1-x).
a(n) = n! * Sum_{k=0..n} (k+1)^(k-1) * binomial(n+k,n-k)/k!.
a(n) ~ sqrt(1 + 2*exp(-1) - sqrt(1 + 4*exp(-1))) * sqrt(1 + 4*exp(-1) - sqrt(1 + 4*exp(-1))) * 2^(n + 3/2) * n^(n-1) / ((sqrt(1 + 4*exp(-1)) - 1)^(5/2) * exp(n) * (2 + exp(1) - exp(1/2)*sqrt(4 + exp(1)))^n). - Vaclav Kotesovec, Aug 05 2025
Showing 1-4 of 4 results.