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 A203695 Vandermonde sequence using x^2 + y^2 applied to the first n triangular numbers: 1,3,6,10,...,n(n+1)/2. 3
 1, 10, 16650, 24928779600, 111827645954579880000, 3822731887490658669088662984000000, 2132112202139633769017736141415928803125840000000000 (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..7. MATHEMATICA f[j_] := j (j + 1)/2; z = 11; 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}] (* A203695 *) Table[v[n + 1]/v[n], {n, 1, z}] (* A203696 *) CROSSREFS Sequence in context: A052498 A179425 A203466 * A181017 A360213 A055321 Adjacent sequences: A203692 A203693 A203694 * A203696 A203697 A203698 KEYWORD nonn AUTHOR Clark Kimberling, Jan 04 2012 STATUS approved

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Last modified May 27 02:41 EDT 2024. Contains 372847 sequences. (Running on oeis4.)