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.

A381594 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 A381601.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 7, 0, 1, 3, 15, 79, 0, 1, 4, 24, 172, 1134, 0, 1, 5, 34, 280, 2475, 18953, 0, 1, 6, 45, 404, 4044, 41280, 353134, 0, 1, 7, 57, 545, 5863, 67365, 766291, 7154751, 0, 1, 8, 70, 704, 7955, 97620, 1246534, 15460284, 155181240, 0, 1, 9, 84, 882, 10344, 132486, 1801536, 25051422, 333896388, 3565276582, 0
Offset: 0

Views

Author

Seiichi Manyama, Mar 01 2025

Keywords

Examples

			Square array begins:
  1,      1,      1,       1,       1,       1,       1, ...
  0,      1,      2,       3,       4,       5,       6, ...
  0,      7,     15,      24,      34,      45,      57, ...
  0,     79,    172,     280,     404,     545,     704, ...
  0,   1134,   2475,    4044,    5863,    7955,   10344, ...
  0,  18953,  41280,   67365,   97620,  132486,  172434, ...
  0, 353134, 766291, 1246534, 1801536, 2439615, 3169770, ...
		

Crossrefs

Columns k=0..1 give A000007, A381601.

Programs

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

Formula

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

A381615 G.f. A(x) satisfies A(x) = 1/(1 - x * A(x*A(x)^3)^3).

Original entry on oeis.org

1, 1, 4, 31, 320, 3969, 56080, 876204, 14860614, 270231265, 5223002719, 106613106181, 2287120272173, 51367948203527, 1204141944566399, 29385603693050274, 744943334951904519, 19580887642660810193, 532781828387893449124, 14984377196395037979472
Offset: 0

Views

Author

Seiichi Manyama, Mar 01 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n, k=1) = 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, 3*j)));

Formula

Let a(n,k) = [x^n] A(x)^k.
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,3*j).

A381595 G.f. A(x) satisfies A(x) = 1/(1 - x * A(x) * A(x*A(x)))^3.

Original entry on oeis.org

1, 3, 24, 280, 4044, 67365, 1246534, 25051422, 538836147, 12279937669, 294374405652, 7382843258466, 192917842671564, 5235276617405133, 147163222059602313, 4275948043251399950, 128196303568520249238, 3959890522003241945409, 125863828745364900374059
Offset: 0

Views

Author

Seiichi Manyama, Mar 01 2025

Keywords

Crossrefs

Column k=3 of A381594.

Programs

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

Formula

See A381594.
G.f.: B(x)^3, where B(x) is the g.f. of A381601.

A381649 G.f. A(x) satisfies A(x) = 1 + x * A(x)^2 * A(x*A(x)^3)^3.

Original entry on oeis.org

1, 1, 5, 44, 510, 7024, 109362, 1871530, 34590180, 682396379, 14251399805, 313170119013, 7207845252630, 173129413258492, 4327373963163746, 112289379643018983, 3018922654575996866, 83951253980821314446, 2411137697712963195801, 71427857356498491780290
Offset: 0

Views

Author

Seiichi Manyama, Mar 03 2025

Keywords

Crossrefs

Column k=1 of A381648.

Programs

  • 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, 3*j)));

Formula

See A381648.
Showing 1-4 of 4 results.