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.

A385425 Expansion of e.g.f. exp( -LambertW(-arcsinh(x)) ).

Original entry on oeis.org

1, 1, 3, 15, 113, 1145, 14499, 220703, 3932865, 80342577, 1851286755, 47510525007, 1344106404849, 41562628517865, 1394711974335939, 50480840239135455, 1960392617938419969, 81309789407316485217, 3587373056789171999811, 167762667997938465311247
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(-asinh(x)))))

Formula

E.g.f. A(x) satisfies A(x) = exp( arcsinh(x) * A(x) ).
E.g.f. A(x) satisfies A(x) = ( x + sqrt(x^2 + 1) )^A(x).
a(n) = Sum_{k=0..n} (k+1)^(k-1) * i^(n-k) * A385343(n,k), where i is the imaginary unit.
From Vaclav Kotesovec, Jun 28 2025: (Start)
a(n) ~ 2^n * exp((exp(-1) - 1)*n + 3/2) * n^(n-1) / (sqrt(1 + exp(2*exp(-1))) * (exp(2*exp(-1)) - 1)^(n - 1/2)).
Equivalently, a(n) ~ n^(n-1) / (sqrt(cosh(exp(-1))) * sinh(exp(-1))^(n - 1/2) * exp(n - 3/2)). (End)

A385426 Expansion of e.g.f. (1/x) * Series_Reversion( x * exp(-arcsin(x)) ).

Original entry on oeis.org

1, 1, 3, 17, 145, 1665, 24115, 422305, 8681985, 205042625, 5471351875, 162811832625, 5345929731025, 192007183247425, 7488448738333875, 315170338129570625, 14238153926819850625, 687220571240324330625, 35293921478604240911875, 1921751625123502012140625
Offset: 0

Views

Author

Seiichi Manyama, Jun 28 2025

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(serreverse(x*exp(-asin(x)))/x))

Formula

E.g.f. A(x) satisfies A(x) = exp( arcsin(x*A(x)) ).
a(n) = Sum_{k=0..n} (n+1)^(k-1) * A385343(n,k).

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
Showing 1-3 of 3 results.