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.

A384944 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 A384941.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 4, 0, 1, 3, 9, -2, 0, 1, 4, 15, 4, -64, 0, 1, 5, 22, 19, -116, -95, 0, 1, 6, 30, 44, -144, -334, 780, 0, 1, 7, 39, 80, -135, -675, 862, 5230, 0, 1, 8, 49, 128, -75, -1060, 70, 11516, 19228, 0, 1, 9, 60, 189, 51, -1414, -1684, 16953, 59632, -90488, 0
Offset: 0

Views

Author

Seiichi Manyama, Jun 13 2025

Keywords

Examples

			Square array begins:
  1,   1,    1,    1,     1,     1,     1, ...
  0,   1,    2,    3,     4,     5,     6, ...
  0,   4,    9,   15,    22,    30,    39, ...
  0,  -2,    4,   19,    44,    80,   128, ...
  0, -64, -116, -144,  -135,   -75,    51, ...
  0, -95, -334, -675, -1060, -1414, -1644, ...
  0, 780,  862,   70, -1684, -4380, -7869, ...
		

Crossrefs

Columns k=0..1 give A000007, A384941.

Programs

  • PARI
    b(n, k) = if(n*k==0, 0^n, (-1)^n*k*sum(j=1, n, binomial(-n+2*j+k-1, j-1)*b(n-j, 4*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+2*j+k-1,j-1) * b(n-j,4*j)/j. Then A(n,k) = b(n,-k).

A384942 G.f. A(x) satisfies A(x) = 1 + x/A(-x*A(x))^5.

Original entry on oeis.org

1, 1, 5, -5, -135, -110, 3661, 16440, -1375, -827075, -8388505, 2298072, 496514205, 2782147265, 322830120, -164675585390, -1846591014842, -3084367863270, 84920580735040, 845318162940805, 4163798547024100, -18708392155753220, -503209620889452990, -3212928238924865090
Offset: 0

Views

Author

Seiichi Manyama, Jun 13 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n, k=-1) = if(n*k==0, 0^n, (-1)^n*k*sum(j=1, n, binomial(-n+2*j+k-1, j-1)*a(n-j, 5*j)/j));

Formula

See A384945.

A384943 G.f. A(x) satisfies A(x) = 1 + x/A(-x*A(x))^6.

Original entry on oeis.org

1, 1, 6, -9, -244, -39, 11262, 36971, -268890, -3724293, -24899558, 159971919, 3851093928, 9663394063, -197371002600, -2108992348026, -9447769941412, 111942512192787, 2253965670439788, 7917705821761592, -100488750700889250, -1520857626228210483
Offset: 0

Views

Author

Seiichi Manyama, Jun 13 2025

Keywords

Crossrefs

Programs

  • PARI
    a(n, k=-1) = if(n*k==0, 0^n, (-1)^n*k*sum(j=1, n, binomial(-n+2*j+k-1, j-1)*a(n-j, 6*j)/j));

Formula

See A384946.

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.
Showing 1-4 of 4 results.