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.

A379868 E.g.f. A(x) satisfies A(x) = exp(-x*A(x)^2) + x*A(x)^2.

Original entry on oeis.org

1, 0, 1, -1, 25, -101, 2281, -19895, 472305, -6760297, 177126121, -3578690435, 105341330953, -2743981145933, 91092111623241, -2888769295882111, 107832291781283809, -4009180998104138321, 167254334458983887689, -7105017992715364001147, 328862774630320838523321
Offset: 0

Views

Author

Seiichi Manyama, Jan 04 2025

Keywords

Crossrefs

Programs

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

Formula

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

A379878 E.g.f. A(x) satisfies A(x) = exp(-x) + x*A(x)^3.

Original entry on oeis.org

1, 0, 1, 8, 97, 1544, 30673, 732752, 20486401, 656713520, 23755416481, 957430990328, 42552022022497, 2067669370359800, 109058922249721585, 6205740584180119424, 378947624701223801089, 24718152376534891564256, 1715322065909959400535361, 126186162087426817989206888
Offset: 0

Views

Author

Seiichi Manyama, Jan 05 2025

Keywords

Crossrefs

Programs

  • Mathematica
    Table[-n! * Sum[(-2*k-1)^(n-k-1) * Binomial[3*k, k] / (n-k)!, {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Jan 23 2025 *)
  • PARI
    a(n) = -n!*sum(k=0, n, (-2*k-1)^(n-k-1)*binomial(3*k, k)/(n-k)!);

Formula

a(n) = -n! * Sum_{k=0..n} (-2*k-1)^(n-k-1) * binomial(3*k,k)/(n-k)!.
a(n) ~ (-1)^n * sqrt(-LambertW(-8/27) - 1) * 2^n * n^(n-1) / (3 * exp(n) * LambertW(-8/27)^(n + 1/2)). - Vaclav Kotesovec, Jan 23 2025

A379911 E.g.f. A(x) satisfies A(x) = exp(-x*A(x)^3) + x*A(x)^2.

Original entry on oeis.org

1, 0, 1, -4, 53, -656, 11917, -244896, 6080265, -171274240, 5480682041, -195121452032, 7672945614589, -329902678161408, 15405361461450885, -776248476561903616, 41985495698339969681, -2426188309657908936704, 149180887282915274036977, -9725086440331395237937152
Offset: 0

Views

Author

Seiichi Manyama, Jan 05 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n) = -n!*sum(k=0, n, (-3*n+2*k-1)^(n-k-1)*binomial(3*n-k, k)/(n-k)!);

Formula

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

A379932 E.g.f. A(x) satisfies A(x) = ( exp(-x) + x*A(x) )^2.

Original entry on oeis.org

1, 0, 2, 10, 88, 978, 13468, 221338, 4233584, 92458018, 2271283684, 62012911530, 1863436238728, 61124896911154, 2173660174175228, 83304031307483962, 3423089366607304672, 150143469737701318722, 7001969736087834197716, 345972733119776006045386
Offset: 0

Views

Author

Seiichi Manyama, Jan 06 2025

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(4*exp(-2*x)/(1+sqrt(1-4*x*exp(-x)))^2))
    
  • PARI
    a(n) = -2*n!*sum(k=0, n, (-k-2)^(n-k-1)*binomial(2*k+1, k)/(n-k)!);

Formula

E.g.f.: B(x)^2, where B(x) is the e.g.f. of A379879.
a(n) = -2 * n! * Sum_{k=0..n} (-k-2)^(n-k-1) * binomial(2*k+1,k)/(n-k)!.
Showing 1-4 of 4 results.