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 1-5 of 5 results.

A384976 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 A384951.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 5, 3, 0, 1, 4, 9, 10, 5, 0, 1, 5, 14, 22, 20, 6, 0, 1, 6, 20, 40, 51, 34, 2, 0, 1, 7, 27, 65, 105, 105, 45, -20, 0, 1, 8, 35, 98, 190, 248, 188, 18, -102, 0, 1, 9, 44, 140, 315, 501, 526, 255, -175, -312, 0, 1, 10, 54, 192, 490, 912, 1200, 956, 63, -836, -795, 0
Offset: 0

Views

Author

Seiichi Manyama, Jun 14 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, 3, 10,  22,  40,   65,   98, ...
  0, 5, 20,  51, 105,  190,  315, ...
  0, 6, 34, 105, 248,  501,  912, ...
  0, 2, 45, 188, 526, 1200, 2408, ...
		

Crossrefs

Columns k=0..1 give A000007, A384951.

Programs

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

Formula

Let b(n,k) = 0^n if n*k=0, otherwise b(n,k) = (-1)^n * k * Sum_{j=1..n} binomial(-n+j+k-1,j-1) * b(n-j,j)/j. Then A(n,k) = b(n,-k).

A385014 G.f. A(x) satisfies A(x) = 1 + x*A(x)/A(-x*A(x))^2.

Original entry on oeis.org

1, 1, 3, 4, 3, -15, -118, -336, -595, 1467, 20391, 96205, 353686, 574786, -2717256, -30598208, -197828371, -841728699, -2599029153, -1309899955, 56975269295, 522707807733, 3425068059553, 16747743739845, 63468629516172, 111911654532374, -907903172853988, -12555837715110897
Offset: 0

Views

Author

Seiichi Manyama, Jun 15 2025

Keywords

Crossrefs

Programs

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

Formula

See A385018.

A385015 G.f. A(x) satisfies A(x) = 1 + x*A(x)/A(-x*A(x))^3.

Original entry on oeis.org

1, 1, 4, 4, -13, -81, -389, -198, 7455, 44515, 198661, 70243, -5428624, -40239313, -218619844, -408542577, 3648305171, 44441073999, 339489511573, 1430556904456, 2122222427956, -35048613488679, -504238969376070, -3684488832562182, -21342732340391295, -67688326964892247
Offset: 0

Views

Author

Seiichi Manyama, Jun 15 2025

Keywords

Crossrefs

Column k=1 of A385019.
Cf. A384896.

Programs

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

Formula

See A385019.

A385016 G.f. A(x) satisfies A(x) = 1 + x*A(x)/A(-x*A(x))^4.

Original entry on oeis.org

1, 1, 5, 3, -51, -190, -401, 3672, 51925, 151539, -482538, -9063614, -79813421, -183787112, 1737820084, 22402935304, 179028179329, 459719628273, -4012720499801, -61168331089037, -556435825634630, -2299434933774430, 2674772917888194, 157684497102084776
Offset: 0

Views

Author

Seiichi Manyama, Jun 15 2025

Keywords

Crossrefs

Column k=1 of A385020.
Cf. A384941.

Programs

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

Formula

See A385020.

A385013 G.f. A(x) satisfies A(x) = 1 + x*A(x)/A(-x*A(x)^2).

Original entry on oeis.org

1, 1, 2, 4, 9, 19, 37, 52, -25, -630, -3616, -15897, -61476, -215135, -677464, -1823081, -3389900, 2523349, 73121734, 526205851, 2914005085, 14163375846, 62788424920, 255900158756, 945473736954, 3008738746058, 6827204137454, -2853842162077, -171206510083289
Offset: 0

Views

Author

Seiichi Manyama, Jun 15 2025

Keywords

Crossrefs

Column k=1 of A385017.
Cf. A213091.

Programs

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

Formula

See A385017.
Showing 1-5 of 5 results.