OFFSET
1,1
COMMENTS
See A093883 for a discussion and guide to related sequences.
FORMULA
a(n) ~ (2 + sqrt(3))^(sqrt(3)*(2*n+3)/2) * exp((Pi/2 - 4)*n + 3*Pi/4) * n^(4*n) / 2^(2*n). - Vaclav Kotesovec, Nov 21 2023
MATHEMATICA
f[j_] := j (j + 1)/2; z = 11;
u[n_] := Product[f[j]^2 - f[j] f[k] + f[k]^2,
{j, 1, k - 1}]
v[n_] := Product[u[n], {k, 2, n}]
Table[v[n], {n, 1, z}] (* A203693 *)
Table[v[n + 1]/v[n], {n, 1, z}] (* A203694 *)
Table[Product[k^2*(k + 1)^2/4 - k*(k + 1)*(n + 1)*(n + 2)/4 + (n + 1)^2*(n + 2)^2/4, {k, 1, n}], {n, 1, 10}] (* Vaclav Kotesovec, Nov 21 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 04 2012
STATUS
approved