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.

A385424 Expansion of e.g.f. exp( -LambertW(-arcsin(x)) ).

Original entry on oeis.org

1, 1, 3, 17, 137, 1465, 19499, 311873, 5829073, 124796081, 3012319315, 80960234577, 2398138520409, 77630951407529, 2726829925494011, 103300796618253825, 4198494172961579169, 182239547736082960737, 8414068749731088539299, 411754575622058760824593
Offset: 0

Views

Author

Seiichi Manyama, Jun 28 2025

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(-lambertw(-asin(x)))))

Formula

E.g.f. A(x) satisfies A(x) = exp( arcsin(x) * A(x) ).
a(n) = Sum_{k=0..n} (k+1)^(k-1) * A385343(n,k).
a(n) ~ n^(n-1) / (sqrt(cos(exp(-1))) * sin(exp(-1))^(n - 1/2) * exp(n - 3/2)). - Vaclav Kotesovec, Jun 28 2025

A385427 E.g.f. A(x) satisfies A(x) = exp( arcsin(x * A(x)) / A(x) ).

Original entry on oeis.org

1, 1, 1, 2, 13, 100, 861, 9536, 127737, 1938896, 33240185, 639683552, 13601898245, 316356906944, 7998251969813, 218420230243840, 6405441641302641, 200779795515236608, 6699317212660139761, 237070134772942395904, 8868209937245857514365, 349657703494298519409664
Offset: 0

Views

Author

Seiichi Manyama, Jun 28 2025

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; A[] = 1; Do[A[x] = E^(ArcSin[x*A[x]]/A[x]) + O[x]^j // Normal, {j, 1, nmax + 1}]; CoefficientList[A[x], x] * Range[0, nmax]! (* Vaclav Kotesovec, Jul 05 2025 *)
  • PARI
    a385343(n, k) = my(x='x+O('x^(n+1))); n!*polcoef(asin(x)^k/k!, n);
    a(n) = sum(k=0, n, (n-k+1)^(k-1)*a385343(n, k));

Formula

a(n) = Sum_{k=0..n} (n-k+1)^(k-1) * A385343(n,k).
a(n) ~ s*(1 - r^2*s^2)^(3/4) * n^(n-1) / (sqrt(r^2*s^2*(2 + r*sqrt(1 - r^2*s^2) - r^2*s^2) - 1) * exp(n) * r^(n - 1/2)), where r = 0.4947196925654744939290429342422921705036054462455... and s = 1.929162378596122962197524561455700427559144822670... are the roots of the system of equations exp(arcsin(r*s)/s) = s, r*s/sqrt(1 - r^2*s^2) - arcsin(r*s) = s. - Vaclav Kotesovec, Jul 05 2025

A385501 Expansion of e.g.f. (1/x) * Series_Reversion( x * exp(-arctanh(x)) ).

Original entry on oeis.org

1, 1, 3, 18, 165, 2040, 31815, 599760, 13268745, 337115520, 9674678475, 309554784000, 10927053262125, 421849524096000, 17682153623909775, 799730490214656000, 38820939579369572625, 2013202580708487168000, 111081054630965602057875, 6497703571257963896832000
Offset: 0

Views

Author

Seiichi Manyama, Jul 01 2025

Keywords

Crossrefs

Programs

  • Mathematica
    nmax=20; CoefficientList[(1/x) *InverseSeries[Series[x * Exp[-ArcTanh[x]],{x,0,nmax}],x] ,x]Range[0,nmax-1]! (* Stefano Spezia, Jul 01 2025 *)
  • PARI
    a(n) = n!*sum(k=0, n, binomial(n, k)*binomial(n/2+k+1/2, n)/(n+2*k+1));

Formula

E.g.f. A(x) satisfies A(x) = exp( arctanh(x*A(x)) ).
E.g.f. A(x) satisfies A(x) = sqrt( (1+x*A(x))/(1-x*A(x)) ).
a(n) = Sum_{k=0..n} (n+1)^(k-1) * A111594(n,k).
a(n) = n!/2^n * A138020(n) = n! * Sum_{k=0..n} binomial(n,k) * binomial(n/2+k+1/2,n)/(n+2*k+1).
Showing 1-3 of 3 results.