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A203689 Vandermonde sequence using x^2 + y^2 applied to (1,2,6,...,n!). 4
1, 5, 7400, 1515608208000, 67968144879431450715389952000, 2618461740951506934762583974466059060153960058218086400000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See A093883 for a discussion and guide to related sequences.

LINKS

Table of n, a(n) for n=1..6.

MATHEMATICA

f[j_] := j!; z = 8;

u[n_] := Product[f[j]^2 + f[k]^2, {j, 1, k - 1}]

v[n_] := Product[u[n], {k, 2, n}]

Table[v[n], {n, 1, z}] (* A203689 *)

Table[v[n + 1]/v[n], {n, 1, z}] (* A203690 *)

CROSSREFS

Sequence in context: A292334 A202156 A117711 * A116140 A243235 A145530

Adjacent sequences: A203686 A203687 A203688 * A203690 A203691 A203692

KEYWORD

nonn

AUTHOR

Clark Kimberling, Jan 04 2012

STATUS

approved

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Last modified February 4 16:45 EST 2023. Contains 360059 sequences. (Running on oeis4.)