OFFSET
1,2
COMMENTS
It is conjectured that every term of the sequence is an integer.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..16
FORMULA
a(n) ~ c * A * n^(n^3/3 - n^2/4 - 7*n/12 + 17/24) * (2*Pi)^(n^2/4 - 3*n/4) / exp(4*n^3/9 - 7*n^2/8 - n + 1/12), where A is the Glaisher-Kinkelin constant A074962 and c = 0.488888619502150098591650327163991582267254151817880403495924251381414248582... (from A203482). - Vaclav Kotesovec, Nov 20 2023
MATHEMATICA
f[j_] := j!; z = 10;
v[n_] := Product[Product[f[k] + f[j], {j, 1, k - 1}], {k, 2, n}]
d[n_] := Product[(i - 1)!, {i, 1, n}] (* A000178 *)
Table[v[n], {n, 1, z}] (* A203482 *)
Table[v[n + 1]/v[n], {n, 1, z - 1}] (* A203483 *)
Table[v[n]/d[n], {n, 1, 10}] (* this sequence *)
Table[Product[j! + k!, {j, 1, n}, {k, 1, j-1}] / BarnesG[n+1], {n, 1, 10}] (* Vaclav Kotesovec, Nov 20 2023 *)
PROG
(Magma)
BarnesG:= func< n | (&*[Factorial(k): k in [0..n-2]]) >;
A203510:= func< n | n eq 1 select 1 else (&*[(&*[Factorial(j) + Factorial(k): k in [1..j-1]]): j in [2..n]])/BarnesG(n+1) >;
[A203510(n): n in [1..13]]; // G. C. Greubel, Feb 24 2024
(SageMath)
def BarnesG(n): return product(factorial(j) for j in range(1, n-1))
def A203510(n): return product(product(factorial(j)+factorial(k) for k in range(1, j)) for j in range(1, n+1))/BarnesG(n+1)
[A203510(n) for n in range(1, 14)] # G. C. Greubel, Feb 24 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 03 2012
STATUS
approved