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.

A362043 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 * binomial(n-2*j,j)/(n-2*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, 5, 1, 1, 1, 1, 4, 9, 11, 1, 1, 1, 1, 5, 13, 21, 31, 1, 1, 1, 1, 6, 17, 31, 81, 106, 1, 1, 1, 1, 7, 21, 41, 151, 351, 337, 1, 1, 1, 1, 8, 25, 51, 241, 736, 1233, 1205, 1, 1, 1, 1, 9, 29, 61, 351, 1261, 2689, 5769, 5021, 1
Offset: 0

Views

Author

Seiichi Manyama, Apr 15 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,  5,  9,  13,  17,  21,  25, ...
  1, 11, 21,  31,  41,  51,  61, ...
  1, 31, 81, 151, 241, 351, 481, ...
		

Crossrefs

Columns k=0..2 give A000012, A190865, A001470.
Main diagonal gives A362173.
T(n,2*n) gives A362300.
T(n,6*n) gives A362301.

Programs

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

Formula

E.g.f. of column k: exp(x + k*x^3/6).
T(n,k) = T(n-1,k) + k * binomial(n-1,2) * T(n-3,k) for n > 2.
T(n,k) = n! * Sum_{j=0..floor(n/3)} (k/6)^j / (j! * (n-3*j)!).

A362173 a(n) = n! * Sum_{k=0..floor(n/3)} (n/6)^k * binomial(n-2*k,k)/(n-2*k)!.

Original entry on oeis.org

1, 1, 1, 4, 17, 51, 481, 3676, 18369, 272917, 3011201, 21058236, 427112401, 6160655359, 55380250017, 1423658493076, 25361574327041, 278603741558601, 8673295084155649, 183914415577719892, 2387417408385462801, 87273239189497636171, 2146479566819857007201
Offset: 0

Views

Author

Seiichi Manyama, Apr 14 2023

Keywords

Crossrefs

Main diagonal of A362043.

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp((-2*lambertw(-x^3/2))^(1/3))/(1+lambertw(-x^3/2))))

Formula

a(n) = n! * [x^n] exp(x + n*x^3/6).
E.g.f.: exp( ( -2*LambertW(-x^3/2) )^(1/3) ) / (1 + LambertW(-x^3/2)).

A362305 a(n) = n! * Sum_{k=0..floor(n/3)} (-n)^k * binomial(n-2*k,k)/(n-2*k)!.

Original entry on oeis.org

1, 1, 1, -17, -95, -299, 12241, 122011, 642433, -41645015, -597247199, -4407324569, 390913189921, 7315513279933, 69439658097265, -7816418805235949, -180448412456686079, -2093964182367814319, 285679499679525805633, 7844019340520912230495
Offset: 0

Views

Author

Seiichi Manyama, Apr 15 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp((lambertw(3*x^3)/3)^(1/3))/(1+lambertw(3*x^3))))

Formula

a(n) = A362302(n,6*n).
a(n) = n! * [x^n] exp(x - n*x^3).
E.g.f.: exp( ( LambertW(3*x^3)/3 )^(1/3) ) / (1 + LambertW(3*x^3)).

A362323 a(n) = n! * Sum_{k=0..floor(n/5)} n^k / (k! * (n-5*k)!).

Original entry on oeis.org

1, 1, 1, 1, 1, 601, 4321, 17641, 53761, 136081, 181742401, 2415576241, 17245198081, 87699217321, 355981385761, 736792782125401, 14287010845685761, 145634558983324321, 1037210264169367681, 5794253172081059041, 16246379099801447769601
Offset: 0

Views

Author

Seiichi Manyama, Apr 16 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp((-lambertw(-5*x^5)/5)^(1/5))/(1+lambertw(-5*x^5))))

Formula

a(n) = n! * [x^n] exp(x + n*x^5).
E.g.f.: exp( ( -LambertW(-5*x^5)/5 )^(1/5) ) / (1 + LambertW(-5*x^5)).

A362321 a(n) = n! * Sum_{k=0..floor(n/4)} n^k /(k! * (n-4*k)!).

Original entry on oeis.org

1, 1, 1, 1, 97, 601, 2161, 5881, 1303681, 14723857, 90770401, 402581521, 139389608161, 2284512533161, 19946635524817, 122623661651401, 57728368477678081, 1240234284406887841, 14010634784751445441, 110117252571345122977
Offset: 0

Views

Author

Seiichi Manyama, Apr 16 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp((-lambertw(-4*x^4)/4)^(1/4))/(1+lambertw(-4*x^4))))

Formula

a(n) = n! * [x^n] exp(x + n*x^4).
E.g.f.: exp( ( -LambertW(-4*x^4)/4 )^(1/4) ) / (1 + LambertW(-4*x^4)).
Showing 1-5 of 5 results.