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.

A306729 a(n) = Product_{i=0..n, j=0..n} (i! + j!).

Original entry on oeis.org

2, 16, 5184, 9559130112, 109045776752640000000000, 27488263744928988967331390258832998400000000000, 1147897050240877062218236820013018349788772091106840426434074807527014400000000000000
Offset: 0

Views

Author

Vaclav Kotesovec, Mar 06 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Product[i! + j!, {i, 0, n}, {j, 0, n}], {n, 0, 7}]
    Clear[a]; a[n_] := a[n] = If[n == 0, 2, a[n-1] * Product[k! + n!, {k, 0, n}]^2 / (2*n!)]; Table[a[n], {n, 0, 7}] (* Vaclav Kotesovec, Mar 27 2019 *)
    Table[Product[Product[k! + j!, {k, 0, j}], {j, 1, n}]^2 / (2^(n-1) * BarnesG[n + 2]), {n, 0, 7}] (* Vaclav Kotesovec, Mar 27 2019 *)
  • Python
    from math import prod, factorial as f
    def a(n): return prod(f(i)+f(j) for i in range(n) for j in range(n))
    print([a(n) for n in range(1, 8)]) # Michael S. Branicky, Feb 16 2021

Formula

a(n) ~ c * 2^(n^2/2 + 2*n) * Pi^(n^2/2 + n) * n^(2*n^3/3 + 2*n^2 + 11*n/6 + 5/2) / exp(8*n^3/9 + 2*n^2 + n), where c = A324569 = 62.14398692334529025548974541735...
a(n) = a(n-1) * A323717(n)^2 / (2*n!). - Vaclav Kotesovec, Mar 28 2019

A203483 a(n) = v(n+1)/v(n), where v = A203482.

Original entry on oeis.org

3, 56, 19500, 267841728, 236189890379520, 19303349192505048268800, 199126474924007956512865886208000, 339543987407937097660189431863908761600000000, 121553118121801544803671246298148699436481551316864204800000
Offset: 1

Views

Author

Clark Kimberling, Jan 03 2012

Keywords

Crossrefs

Programs

  • Magma
    [(&*[Factorial(k) + Factorial(n+1): k in [1..n]]): n in [1..16]]; // G. C. Greubel, Aug 29 2023
    
  • Mathematica
    (* First program *)
    f[j_]:= j!; z = 10;
    v[n_]:= Product[Product[f[k] + f[j], {j,k-1}], {k,2,n}]
    d[n_]:= Product[(i-1)!, {i, n}]   (* A000178 *)
    Table[v[n], {n,z}]                (* A203482 *)
    Table[v[n+1]/v[n], {n,z-1}]       (* this sequence *)
    Table[v[n]/d[n], {n,10}]          (* A203510 *)
    (* Second program *)
    Table[Product[k!+(n+1)!, {k,n}], {n,15}] (* G. C. Greubel, Aug 29 2023 *)
  • SageMath
    [product(factorial(k) + factorial(n+1) for k in range(1,n+1)) for n in range(1,16)] # G. C. Greubel, Aug 29 2023

Formula

a(n) = Product_{k=1..n} (k! + (n+1)!). - G. C. Greubel, Aug 29 2023
From Vaclav Kotesovec, Nov 20 2023: (Start)
a(n) ~ (n+1)!^n.
a(n) ~ (2*Pi)^(n/2) * n^(n^2 + 3*n/2) / exp(n^2 - 13/12). (End)

A203308 a(n) = A203306(n+1)/A203306(n).

Original entry on oeis.org

1, 1, 20, 9108, 153675648, 153926018668800, 13624548214772203315200, 148312029363286484759480524800000, 262925014428462931164318003384701335633920000, 96950311125839455466119755365478799838570665250861875200000
Offset: 0

Views

Author

Clark Kimberling, Jan 01 2012

Keywords

Crossrefs

Programs

  • Magma
    F:= Factorial; [1] cat [(&*[F(n+1) - F(j): j in [1..n]]): n in [1..20]]; // G. C. Greubel, Aug 30 2023
    
  • Mathematica
    (* First program *)
    f[j_]:= j!; z = 10;
    v[n_]:= Product[Product[f[k] - f[j], {j,k-1}], {k,2,n}]
    Table[v[n], {n,0,z}]          (* A203306 *)
    Table[v[n+1]/v[n], {n,0,z}]   (* A203308 *)
    (* Second program *)
    Table[Product[(n+1)! - k!, {k,n}], {n,0,10}] (* Vaclav Kotesovec, Jan 25 2019 *)
  • Python
    from sympy import factorial as f
    from operator import mul
    from functools import reduce
    def v(n):
        return 1 if n<2 else reduce(mul, (f(k+1) - f(j) for k in range(1,n) for j in range(1, k+1)))
    print([v(n + 1)//v(n) for n in range(16)]) # Indranil Ghosh, Jul 24 2017
    
  • SageMath
    f=factorial; [product(f(n+1) - f(k) for k in range(1,n+1)) for n in range(21)] # G. C. Greubel, Aug 30 2023

Formula

a(n) ~ (2*Pi)^(n/2) * n^(n*(2*n + 3)/2) / exp(n^2 - 13/12). - Vaclav Kotesovec, Jan 25 2019
a(n) = Product_{j=1..n} ((n+1)! - j!). - G. C. Greubel, Aug 30 2023

Extensions

a(0) = 1 prepended by G. C. Greubel, Aug 30 2023

A306193 a(n) = Product_{k=0..n} (1 + n!/k!).

Original entry on oeis.org

2, 4, 18, 392, 81250, 225061452, 9854913828914, 7821195286733052688, 128042318400630042200896962, 48734103316428964151516768659332500, 480771737247108575104717059364582638896056402, 135700420467061659867201490569546772642393389614560348824
Offset: 0

Views

Author

Vaclav Kotesovec, Jan 28 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Product[1 + n!/k!, {k, 0, n}], {n, 0, 12}]

Formula

a(n) = A323717(n) / A000178(n).
a(n) ~ 2 * A * n^(n*(n+1)/2 + 1/12) / exp(n^2/4), where A is the Glaisher-Kinkelin constant A074962.
Showing 1-4 of 4 results.