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.

A384691 E.g.f. A(x) satisfies A(x) = exp( x*A(x) * A(x*A(x))^2 ).

Original entry on oeis.org

1, 1, 7, 112, 2989, 115136, 5899159, 381657928, 30082660633, 2814548348224, 306467497027531, 38242238970083336, 5401465336487870533, 854848596955885610560, 150317821473136130378335, 29159232358630752927016456, 6201999009581132843649181489, 1438725999127826885623788697472
Offset: 0

Views

Author

Seiichi Manyama, Jun 07 2025

Keywords

Crossrefs

Column k=1 of A384692.

Programs

  • Mathematica
    terms = 18; A[] = 0; Do[A[x] = Exp[x*A[x]*A[x*A[x]]^2] + O[x]^terms // Normal, terms]; Range[0,terms-1]!CoefficientList[A[x], x] (* Stefano Spezia, Jun 07 2025 *)
  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, (n+k)^(j-1)*binomial(n, j)*a(n-j, 2*j)));

Formula

See A384692.

A384721 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where column k is the expansion of e.g.f. B(x)^k, where B(x) is the e.g.f. of A384719.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 5, 0, 1, 3, 12, 61, 0, 1, 4, 21, 152, 1281, 0, 1, 5, 32, 279, 3200, 39641, 0, 1, 6, 45, 448, 5937, 98192, 1655713, 0, 1, 7, 60, 665, 9696, 181563, 4053688, 88312869, 0, 1, 8, 77, 936, 14705, 296864, 7430265, 213600200, 5792082817, 0
Offset: 0

Views

Author

Seiichi Manyama, Jun 08 2025

Keywords

Examples

			Square array begins:
  1,     1,     1,      1,      1,      1, ...
  0,     1,     2,      3,      4,      5, ...
  0,     5,    12,     21,     32,     45, ...
  0,    61,   152,    279,    448,    665, ...
  0,  1281,  3200,   5937,   9696,  14705, ...
  0, 39641, 98192, 181563, 296864, 452525, ...
		

Crossrefs

Columns k=0..1 give A000007, A384719.

Programs

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

Formula

A(n,0) = 0^n; A(n,k) = k * Sum_{j=0..n} (n-j+k)^(j-1) * binomial(n,j) * A(n-j,2*j).

A384718 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where column k is the expansion of e.g.f. B(x)^k, where B(x) is the e.g.f. of A052750.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 5, 0, 1, 3, 12, 49, 0, 1, 4, 21, 128, 729, 0, 1, 5, 32, 243, 2000, 14641, 0, 1, 6, 45, 400, 3993, 41472, 371293, 0, 1, 7, 60, 605, 6912, 85683, 1075648, 11390625, 0, 1, 8, 77, 864, 10985, 153664, 2278125, 33554432, 410338673, 0
Offset: 0

Views

Author

Seiichi Manyama, Jun 08 2025

Keywords

Examples

			Square array begins:
  1,     1,     1,     1,      1,      1, ...
  0,     1,     2,     3,      4,      5, ...
  0,     5,    12,    21,     32,     45, ...
  0,    49,   128,   243,    400,    605, ...
  0,   729,  2000,  3993,   6912,  10985, ...
  0, 14641, 41472, 85683, 153664, 253125, ...
		

Crossrefs

Columns k=0..2 give A000007, A052750, A097629(n+1).

Programs

  • PARI
    a(n, k) = if(n==0, 1, k*(2*n+k)^(n-1));

Formula

A(n,k) = k * (2*n+k)^(n-1) for n > 0.
Showing 1-3 of 3 results.