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.

A384652 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where column k is the expansion of B(x)^k, where B(x) is the g.f. of A384145.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 5, 8, 0, 1, 4, 9, 20, 44, 0, 1, 5, 14, 37, 108, 298, 0, 1, 6, 20, 60, 198, 716, 2359, 0, 1, 7, 27, 90, 321, 1290, 5554, 21112, 0, 1, 8, 35, 128, 485, 2064, 9821, 48838, 209175, 0, 1, 9, 44, 175, 699, 3091, 15452, 84888, 476714, 2262121, 0
Offset: 0

Views

Author

Seiichi Manyama, Jun 06 2025

Keywords

Examples

			Square array begins:
  1,    1,    1,    1,     1,     1,     1, ...
  0,    1,    2,    3,     4,     5,     6, ...
  0,    2,    5,    9,    14,    20,    27, ...
  0,    8,   20,   37,    60,    90,   128, ...
  0,   44,  108,  198,   321,   485,   699, ...
  0,  298,  716, 1290,  2064,  3091,  4434, ...
  0, 2359, 5554, 9821, 15452, 22805, 32315, ...
		

Crossrefs

Columns k=0..1 give A000007, A384145.

Programs

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

Formula

A(n,0) = 0^n; A(n,k) = k * Sum_{j=0..n} binomial(3*n-2*j+k,j)/(3*n-2*j+k) * A(n-j,j).

A384649 G.f. A(x) satisfies A(x) = 1/( 1 - x*A(x*A(x)^4) ).

Original entry on oeis.org

1, 1, 2, 9, 56, 432, 3935, 40820, 471633, 5980210, 82329140, 1220547845, 19359684220, 326799737576, 5844913732057, 110341722975077, 2191461358459051, 45656013573862832, 995196646595460516, 22644288881875546322, 536706817952488705651, 13225669497771610891404
Offset: 0

Views

Author

Seiichi Manyama, Jun 06 2025

Keywords

Crossrefs

Column k=1 of A384653.

Programs

  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(4*n-3*j+k, j)/(4*n-3*j+k)*a(n-j, j)));

Formula

See A384653.

A384650 G.f. A(x) satisfies A(x) = 1/( 1 - x*A(x*A(x)^5) ).

Original entry on oeis.org

1, 1, 2, 10, 69, 592, 6052, 70870, 928497, 13404514, 210892157, 3584892350, 65390514877, 1272723903336, 26307949481077, 575201364472316, 13255835789428863, 320999903683710948, 8145524458876305526, 216062918679078474529, 5977572987203090333399
Offset: 0

Views

Author

Seiichi Manyama, Jun 06 2025

Keywords

Crossrefs

Column k=1 of A384654.

Programs

  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(5*n-4*j+k, j)/(5*n-4*j+k)*a(n-j, j)));

Formula

See A384654.

A384680 G.f. A(x) satisfies A(x) = 1/( 1 - x*A(x)*A(x*A(x)^3) ).

Original entry on oeis.org

1, 1, 3, 15, 100, 805, 7442, 76750, 866818, 10586499, 138549918, 1929878820, 28459172110, 442421488758, 7225177328165, 123586748434192, 2208493015533530, 41138303109509415, 797178212982793708, 16041390159326400966, 334654194086236031816, 7227174934846895031544
Offset: 0

Views

Author

Seiichi Manyama, Jun 06 2025

Keywords

Crossrefs

Column k=1 of A384681.

Programs

  • Mathematica
    terms = 22; A[] = 0; Do[A[x] = 1/(1-x*A[x]*A[x*A[x]^3]) + O[x]^terms // Normal, terms]; CoefficientList[A[x], x] (* Stefano Spezia, Jun 07 2025 *)
  • PARI
    a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(3*n-j+k, j)/(3*n-j+k)*a(n-j, j)));

Formula

See A384681.
Showing 1-4 of 4 results.