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.

A143925 E.g.f. A(x) satisfies A(x) = exp(x + x^2*A'(x)).

Original entry on oeis.org

1, 1, 3, 25, 397, 10061, 369061, 18415825, 1197307161, 98248658905, 9928361978281, 1211474323983221, 175635827999270629, 29845580180227776277, 5876070628821158239293, 1327055145216772464211321, 340793190982323564066166321, 98752652958563191504390390577
Offset: 0

Views

Author

Paul D. Hanna, Sep 06 2008

Keywords

Crossrefs

Programs

  • PARI
    {a(n)=local(A=1+x);for(i=0,n,A=exp(x+x^2*deriv(A)+x*O(x^n)));n!*polcoeff(A,n)}

Formula

a(n) ~ c * (n!)^2, where c = 0.80799863989712622039... - Vaclav Kotesovec, Feb 22 2014
a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} (1 + k) * k * binomial(n-1,k) * a(k) * a(n-1-k). - Seiichi Manyama, Jul 24 2025

A386511 a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} (1 + k) * binomial(k+2,3) * binomial(n-1,k) * a(k) * a(n-1-k).

Original entry on oeis.org

1, 1, 3, 43, 1889, 198661, 42947941, 17142237365, 11658352652969, 12696712215226345, 21077148910182673081, 51239319321668728761281, 176469705716413028667777349, 837352955330191136544190873989, 5345677943448502627987168885274813, 44983970430636919384496638254796550221
Offset: 0

Views

Author

Seiichi Manyama, Jul 24 2025

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, (1+j)*binomial(j+2, 3)*binomial(i-1, j)*v[j+1]*v[i-j])); v;

Formula

E.g.f. A(x) satisfies A(x) = exp( x + x*Sum_{k=1..3} binomial(2,k-1) * x^k/k! * (d^k/dx^k A(x)) ).

A386512 a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} (1 + k) * binomial(k+3,4) * binomial(n-1,k) * a(k) * a(n-1-k).

Original entry on oeis.org

1, 1, 3, 52, 3325, 598906, 255199051, 226888865575, 382997189880593, 1140957869006770561, 5659169551911928576531, 44571684957086887771692731, 535930324156886354251195391269, 9517054240482595566592327616630965, 242627830243798770154326313268171970697
Offset: 0

Views

Author

Seiichi Manyama, Jul 24 2025

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, (1+j)*binomial(j+3, 4)*binomial(i-1, j)*v[j+1]*v[i-j])); v;

Formula

E.g.f. A(x) satisfies A(x) = exp( x + x*Sum_{k=1..4} binomial(3,k-1) * x^k/k! * (d^k/dx^k A(x)) ).

A386513 a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} (1 + k) * binomial(k+4,5) * binomial(n-1,k) * a(k) * a(n-1-k).

Original entry on oeis.org

1, 1, 3, 61, 5365, 1529521, 1165598707, 2064316175293, 7646264783133257, 54571471797846058921, 702880914451594090404601, 15486578255494092846454504205, 558260219954065540499622238580509, 31707506930744375037184483066962163261, 2747328696602823034266635550466257234352117
Offset: 0

Views

Author

Seiichi Manyama, Jul 24 2025

Keywords

Crossrefs

Programs

  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, (1+j)*binomial(j+4, 5)*binomial(i-1, j)*v[j+1]*v[i-j])); v;

Formula

E.g.f. A(x) satisfies A(x) = exp( x + x*Sum_{k=1..5} binomial(4,k-1) * x^k/k! * (d^k/dx^k A(x)) ).
Showing 1-4 of 4 results.