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A203689
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Vandermonde sequence using x^2 + y^2 applied to (1,2,6,...,n!).
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4
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OFFSET
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1,2
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COMMENTS
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See A093883 for a discussion and guide to related sequences.
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LINKS
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FORMULA
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a(n) ~ c * n^(2*n^3/3 + n^2/2 - 7*n/6 - 3/4) * (2*Pi)^(n*(n-1)/2) / exp(8*n^3/9 - n^2/4 - 2*n), where c = 0.574053995428296820717722993471497472923951255369819486673614046900594637219... - Vaclav Kotesovec, Nov 21 2023
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MATHEMATICA
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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 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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