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 1-6 of 6 results.

A362377 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * Sum_{j=0..floor(n/2)} (k/2)^j * (j+1)^(n-j-1) / (j! * (n-2*j)!).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 7, 1, 1, 1, 4, 13, 34, 1, 1, 1, 5, 19, 85, 216, 1, 1, 1, 6, 25, 154, 701, 1696, 1, 1, 1, 7, 31, 241, 1456, 7261, 15898, 1, 1, 1, 8, 37, 346, 2481, 18136, 89125, 173468, 1, 1, 1, 9, 43, 469, 3776, 35761, 260002, 1277865, 2161036, 1
Offset: 0

Views

Author

Seiichi Manyama, Apr 20 2023

Keywords

Examples

			Square array begins:
  1,    1,    1,     1,     1,     1,     1, ...
  1,    1,    1,     1,     1,     1,     1, ...
  1,    2,    3,     4,     5,     6,     7, ...
  1,    7,   13,    19,    25,    31,    37, ...
  1,   34,   85,   154,   241,   346,   469, ...
  1,  216,  701,  1456,  2481,  3776,  5341, ...
  1, 1696, 7261, 18136, 35761, 61576, 97021, ...
		

Crossrefs

Columns k=0..3 give A000012, A143740, A125500, A362380.

Programs

  • PARI
    T(n, k) = n! * sum(j=0, n\2, (k/2)^j*(j+1)^(n-j-1)/(j!*(n-2*j)!));

Formula

E.g.f. A_k(x) of column k satisfies A_k(x) = exp(x + k*x^2/2 * A_k(x)).
A_k(x) = exp(x - LambertW(-k*x^2/2 * exp(x))).
A_k(x) = -2 * LambertW(-k*x^2/2 * exp(x))/(k*x^2) for k > 0.

A362392 E.g.f. satisfies A(x) = exp(x + x^3 * A(x)).

Original entry on oeis.org

1, 1, 1, 7, 49, 241, 2041, 26041, 282913, 3449377, 57170161, 973059121, 16847893921, 343341027745, 7680743819113, 175958943331081, 4375517632543681, 118932887426911681, 3374685950589927649, 100735118425384221025, 3217474234925998764481
Offset: 0

Views

Author

Seiichi Manyama, Apr 20 2023

Keywords

Crossrefs

Column k=6 of A362378.

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x-lambertw(-x^3*exp(x)))))

Formula

E.g.f.: exp(x - LambertW(-x^3 * exp(x))) = -LambertW(-x^3 * exp(x))/x^3.
a(n) = n! * Sum_{k=0..floor(n/3)} (k+1)^(n-2*k-1) / (k! * (n-3*k)!).

A362490 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * Sum_{j=0..floor(n/3)} (k/6)^j * (3*j+1)^(n-2*j-1) / (j! * (n-3*j)!).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 17, 1, 1, 1, 1, 4, 33, 161, 1, 1, 1, 1, 5, 49, 321, 1351, 1, 1, 1, 1, 6, 65, 481, 2841, 12391, 1, 1, 1, 1, 7, 81, 641, 4471, 31641, 153385, 1, 1, 1, 1, 8, 97, 801, 6241, 57751, 498849, 2388905, 1
Offset: 0

Views

Author

Seiichi Manyama, Apr 22 2023

Keywords

Examples

			Square array begins:
  1,    1,    1,    1,    1,    1,     1, ...
  1,    1,    1,    1,    1,    1,     1, ...
  1,    1,    1,    1,    1,    1,     1, ...
  1,    2,    3,    4,    5,    6,     7, ...
  1,   17,   33,   49,   65,   81,    97, ...
  1,  161,  321,  481,  641,  801,   961, ...
  1, 1351, 2841, 4471, 6241, 8151, 10201, ...
		

Crossrefs

Columns k=0..3 give A000012, A362477, A362478, A362479.
Cf. A362378.

Programs

  • PARI
    T(n, k) = n! * sum(j=0, n\3, (k/6)^j*(3*j+1)^(n-2*j-1)/(j!*(n-3*j)!));

Formula

E.g.f. A_k(x) of column k satisfies A_k(x) = exp(x + k*x^3/6 * A_k(x)^3).
A_k(x) = exp(x - LambertW(-k*x^3/2 * exp(3*x))/3).
A_k(x) = ( -2 * LambertW(-k*x^3/2 * exp(3*x))/(k*x^3) )^(1/3) for k > 0.

A362381 E.g.f. satisfies A(x) = exp(x + x^3/6 * A(x)).

Original entry on oeis.org

1, 1, 1, 2, 9, 41, 191, 1191, 9353, 77897, 704861, 7352621, 85323921, 1058023825, 14155416003, 206100005931, 3217934262481, 53320102598481, 939087824434009, 17562552535939705, 346668611080774081, 7196193133818592961, 156944931623033340711
Offset: 0

Views

Author

Seiichi Manyama, Apr 20 2023

Keywords

Crossrefs

Column k=1 of A362378.

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x-lambertw(-x^3/6*exp(x)))))

Formula

E.g.f.: exp(x - LambertW(-x^3/6 * exp(x))) = -6 * LambertW(-x^3/6 * exp(x))/x^3.
a(n) = n! * Sum_{k=0..floor(n/3)} (1/6)^k * (k+1)^(n-2*k-1) / (k! * (n-3*k)!).

A362390 E.g.f. satisfies A(x) = exp(x + x^3/3 * A(x)).

Original entry on oeis.org

1, 1, 1, 3, 17, 81, 441, 3641, 33825, 318753, 3505521, 45095601, 616484001, 9013086369, 145909533225, 2556431401161, 47388760825281, 937507626246081, 19840711661183457, 443937299529447009, 10456231167451597761, 259738234024404363201
Offset: 0

Views

Author

Seiichi Manyama, Apr 20 2023

Keywords

Crossrefs

Column k=2 of A362378.

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x-lambertw(-x^3/3*exp(x)))))

Formula

E.g.f.: exp(x - LambertW(-x^3/3 * exp(x))) = -3 * LambertW(-x^3/3 * exp(x))/x^3.
a(n) = n! * Sum_{k=0..floor(n/3)} (1/3)^k * (k+1)^(n-2*k-1) / (k! * (n-3*k)!).

A362391 E.g.f. satisfies A(x) = exp(x + x^3/2 * A(x)).

Original entry on oeis.org

1, 1, 1, 4, 25, 121, 751, 7351, 73417, 749449, 9477181, 136883341, 2041250641, 33289802833, 608025141907, 11815916748091, 242532915013201, 5369303859003601, 126896359555326745, 3153096762426186553, 82705881733348530241, 2293511922269658189121
Offset: 0

Views

Author

Seiichi Manyama, Apr 20 2023

Keywords

Crossrefs

Column k=3 of A362378.

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x-lambertw(-x^3/2*exp(x)))))

Formula

E.g.f.: exp(x - LambertW(-x^3/2 * exp(x))) = -2 * LambertW(-x^3/2 * exp(x))/x^3.
a(n) = n! * Sum_{k=0..floor(n/3)} (1/2)^k * (k+1)^(n-2*k-1) / (k! * (n-3*k)!).
Showing 1-6 of 6 results.