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.

A382806 a(n) = Sum_{k=0..n} (k!)^2 * binomial(k+2,2) * Stirling1(n,k)^2.

Original entry on oeis.org

1, 3, 27, 588, 24612, 1669128, 165049224, 22269896064, 3918921022656, 870149951146944, 237662482188210624, 78249086559726140160, 30547324837444471084800, 13946361918619108837939200, 7359961832428044552536217600, 4444946383758589481684168540160
Offset: 0

Views

Author

Seiichi Manyama, Apr 05 2025

Keywords

Crossrefs

Main diagonal of A382800.
Cf. A382738.

Programs

  • PARI
    a(n) = sum(k=0, n, k!^2*binomial(k+2, 2)*stirling(n, k, 1)^2);

Formula

a(n) == 0 (mod 3) for n > 0.
a(n) = (n!)^2 * [(x*y)^n] 1 / (1 - log(1-x) * log(1-y))^3.
a(n) = (n!)^2 * [(x*y)^n] 1 / (1 - log(1+x) * log(1+y))^3.
a(n) ~ sqrt(Pi) * n^(2*n + 5/2) / (2 * (exp(1) - 1)^(2*n+3)). - Vaclav Kotesovec, Apr 05 2025

A382799 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where A(n,k) = n! * k! * [x^n * y^k] 1 / (1 - log(1-x) * log(1-y))^2.

Original entry on oeis.org

1, 0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 4, 14, 4, 0, 0, 12, 40, 40, 12, 0, 0, 48, 144, 260, 144, 48, 0, 0, 240, 648, 1284, 1284, 648, 240, 0, 0, 1440, 3528, 6936, 9588, 6936, 3528, 1440, 0, 0, 10080, 22608, 42744, 65928, 65928, 42744, 22608, 10080, 0, 0, 80640, 166896, 300240, 476808, 581952, 476808, 300240, 166896, 80640, 0
Offset: 0

Views

Author

Seiichi Manyama, Apr 05 2025

Keywords

Examples

			Square array begins:
  1,  0,   0,    0,     0,      0, ...
  0,  2,   2,    4,    12,     48, ...
  0,  2,  14,   40,   144,    648, ...
  0,  4,  40,  260,  1284,   6936, ...
  0, 12, 144, 1284,  9588,  65928, ...
  0, 48, 648, 6936, 65928, 581952, ...
		

Crossrefs

Main diagonal gives A382804.

Programs

  • PARI
    a(n, k) = sum(j=0, min(n, k), j!*(j+1)!*abs(stirling(n, j, 1)*stirling(k, j, 1)));

Formula

E.g.f.: 1 / (1 - log(1-x) * log(1-y))^2.
A(n,k) = A(k,n).
A(n,k) = Sum_{j=0..min(n,k)} j! * (j+1)! * |Stirling1(n,j)| * |Stirling1(k,j)|.

A382825 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where A(n,k) = n! * k! * [x^n * y^k] 1 / ( (1-x) * (1-y) * (1 - log(1-x) * log(1-y))^3 ).

Original entry on oeis.org

1, 1, 1, 2, 4, 2, 6, 11, 11, 6, 24, 39, 55, 39, 24, 120, 174, 255, 255, 174, 120, 720, 942, 1338, 1623, 1338, 942, 720, 5040, 6012, 8106, 10434, 10434, 8106, 6012, 5040, 40320, 44244, 56292, 72762, 82116, 72762, 56292, 44244, 40320, 362880, 369072, 442860, 560988, 668580, 668580, 560988, 442860, 369072, 362880
Offset: 0

Views

Author

Seiichi Manyama, Apr 06 2025

Keywords

Examples

			Square array begins:
    1,   1,    2,     6,     24,     120, ...
    1,   4,   11,    39,    174,     942, ...
    2,  11,   55,   255,   1338,    8106, ...
    6,  39,  255,  1623,  10434,   72762, ...
   24, 174, 1338, 10434,  82116,  668580, ...
  120, 942, 8106, 72762, 668580, 6302028, ...
		

Crossrefs

Main diagonal gives A382828.

Programs

  • PARI
    a(n, k) = sum(j=0, min(n, k), j!^2*binomial(j+2, 2)*abs(stirling(n+1, j+1, 1)*stirling(k+1, j+1, 1)));

Formula

E.g.f.: 1 / ( (1-x) * (1-y) * (1 - log(1-x) * log(1-y))^3 ).
A(n,k) = A(k,n).
A(n,k) = Sum_{j=0..min(n,k)} (j!)^2 * binomial(j+2,2) * |Stirling1(n+1,j+1)| * |Stirling1(k+1,j+1)|.

A382802 Square array A(n,k), n >= 1, k >= 1, read by antidiagonals downwards, where A(n,k) = n! * k! * [x^n * y^k] (1/3) * (1 / (1 - log(1-x) * log(1-y))^3 - 1).

Original entry on oeis.org

1, 1, 1, 2, 9, 2, 6, 26, 26, 6, 24, 94, 196, 94, 24, 120, 424, 996, 996, 424, 120, 720, 2312, 5448, 8204, 5448, 2312, 720, 5040, 14832, 33816, 58544, 58544, 33816, 14832, 5040, 40320, 109584, 238656, 431632, 556376, 431632, 238656, 109584, 40320
Offset: 1

Views

Author

Seiichi Manyama, Apr 05 2025

Keywords

Examples

			Square array begins:
    1,    1,     2,      6,      24,      120, ...
    1,    9,    26,     94,     424,     2312, ...
    2,   26,   196,    996,    5448,    33816, ...
    6,   94,   996,   8204,   58544,   431632, ...
   24,  424,  5448,  58544,  556376,  5017480, ...
  120, 2312, 33816, 431632, 5017480, 55016408, ...
		

Crossrefs

Programs

  • PARI
    a(n, k) = sum(j=0, min(n, k), j!^2*binomial(j+2, 2)*abs(stirling(n, j, 1)*stirling(k, j, 1)))/3;

Formula

E.g.f.: (1/3) * (1 / (1 - log(1-x) * log(1-y))^3 - 1).
A(n,k) = A(k,n).
A(n,k) = (1/3) * A382800(n,k).
Showing 1-4 of 4 results.