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.

A378239 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,0) = 0^n and T(n,k) = k * Sum_{r=0..n} binomial(n,r) * binomial(2*n+2*r+k,n)/(2*n+2*r+k) for k > 0.

Original entry on oeis.org

1, 1, 0, 1, 2, 0, 1, 4, 12, 0, 1, 6, 28, 100, 0, 1, 8, 48, 248, 968, 0, 1, 10, 72, 452, 2480, 10208, 0, 1, 12, 100, 720, 4680, 26688, 113792, 0, 1, 14, 132, 1060, 7728, 51504, 301648, 1318832, 0, 1, 16, 168, 1480, 11800, 87104, 591312, 3531424, 15732064, 0
Offset: 0

Views

Author

Seiichi Manyama, Nov 20 2024 based on suggestions from Mikhail Kurkov

Keywords

Examples

			Square array begins:
  1,      1,      1,      1,       1,       1,       1, ...
  0,      2,      4,      6,       8,      10,      12, ...
  0,     12,     28,     48,      72,     100,     132, ...
  0,    100,    248,    452,     720,    1060,    1480, ...
  0,    968,   2480,   4680,    7728,   11800,   17088, ...
  0,  10208,  26688,  51504,   87104,  136352,  202560, ...
  0, 113792, 301648, 591312, 1017184, 1621280, 2454256, ...
		

Crossrefs

Programs

  • PARI
    T(n, k, t=2, u=2) = if(k==0, 0^n, k*sum(r=0, n, binomial(n, r)*binomial(t*n+u*r+k, n)/(t*n+u*r+k)));
    matrix(7, 7, n, k, T(n-1, k-1))

Formula

G.f. A_k(x) of column k satisfies A_k(x) = ( 1 + x * A_k(x)^(2/k) * (1 + A_k(x)^(2/k)) )^k for k > 0.
G.f. of column k: B(x)^k where B(x) is the g.f. of A219534.
B(x)^k = B(x)^(k-1) + x * B(x)^(k+1) + x * B(x)^(k+3). So T(n,k) = T(n,k-1) + T(n-1,k+1) + T(n-1,k+3) for n > 0.

A371681 G.f. satisfies A(x) = ( 1 + x * A(x) * (1 + A(x)) )^3.

Original entry on oeis.org

1, 6, 66, 926, 14706, 251622, 4524786, 84310014, 1613384994, 31521329670, 626151135330, 12608193099294, 256769542135314, 5279533270393446, 109449833201392530, 2285215031994672894, 48011502768234360642, 1014265693597636966662
Offset: 0

Views

Author

Seiichi Manyama, Apr 02 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n, r=3, t=3, u=3) = r*sum(k=0, n, binomial(n, k)*binomial(t*n+u*k+r, n)/(t*n+u*k+r));

Formula

G.f.: B(x)^3 where B(x) is the g.f. of A364167.
a(n) = Sum_{k=0..n} binomial(n,k) * binomial(3*n+3*k+3,n)/(n+k+1).

A378155 G.f. A(x) satisfies A(x) = ( 1 + x * A(x)^(2/3) * (1 + A(x)^(2/3)) )^3.

Original entry on oeis.org

1, 6, 48, 452, 4680, 51504, 591312, 7002864, 84926304, 1049402944, 13165069824, 167239042176, 2146912312064, 27808372643328, 362981425115904, 4769884412086016, 63050983340533248, 837805424714425344, 11184489029495865344, 149935005483457542144, 2017560365768892739584
Offset: 0

Views

Author

Seiichi Manyama, Nov 18 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n, r=3, t=2, u=2) = r*sum(k=0, n, binomial(n, k)*binomial(t*n+u*k+r, n)/(t*n+u*k+r));

Formula

G.f.: B(x)^3 where B(x) is the g.f. of A219534.
a(n) = 3 * Sum_{k=0..n} binomial(n,k) * binomial(2*n+2*k+3,n)/(2*n+2*k+3).

A378156 G.f. A(x) satisfies A(x) = ( 1 + x * A(x)^(1/2) * (1 + A(x)^(1/2)) )^4.

Original entry on oeis.org

1, 8, 72, 720, 7728, 87104, 1017184, 12200640, 149429504, 1861059328, 23498407680, 300110580224, 3870135336192, 50323754919936, 659085377250816, 8686436702866432, 115120162870534144, 1533214282017157120, 20510220228874399744, 275462154992599851008, 3712900128220039372800
Offset: 0

Views

Author

Seiichi Manyama, Nov 18 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n, r=4, t=2, u=2) = r*sum(k=0, n, binomial(n, k)*binomial(t*n+u*k+r, n)/(t*n+u*k+r));

Formula

G.f.: B(x)^4 where B(x) is the g.f. of A219534.
a(n) = 2 * Sum_{k=0..n} binomial(n,k) * binomial(2*n+2*k+4,n)/(n+k+2).

A371680 G.f. satisfies A(x) = ( 1 + x * A(x)^2 * (1 + A(x)) )^2.

Original entry on oeis.org

1, 4, 44, 648, 10960, 200992, 3886928, 78043488, 1611405504, 33998715264, 729793915264, 15886841223936, 349900041893376, 7782694227059712, 174573007616191744, 3944500600180286976, 89696369377912622080, 2051147782339517224960
Offset: 0

Views

Author

Seiichi Manyama, Apr 02 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n, r=2, t=4, u=2) = r*sum(k=0, n, binomial(n, k)*binomial(t*n+u*k+r, n)/(t*n+u*k+r));

Formula

G.f.: B(x)^2 where B(x) is the g.f. of A363380.
a(n) = Sum_{k=0..n} binomial(n,k) * binomial(4*n+2*k+2,n)/(2*n+k+1).
Showing 1-5 of 5 results.