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 A203431 a(n) = v(n+1)/v(n), where v=A203418. 3
 2, 3, 30, 72, 1440, 4536, 142560, 544320, 23950080, 106142400, 6107270400, 30569011200, 2198617344000, 12197035468800, 1061932177152000, 6440034727526400, 662645678542848000, 4347023441080320000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS G. C. Greubel, Table of n, a(n) for n = 1..300 MATHEMATICA f[j_]:= j + Floor[j/2]; z = 20; v[n_]:= Product[Product[f[k] - f[j], {j, k-1}], {k, 2, n}] d[n_]:= Product[(i-1)!, {i, n}] Table[v[n], {n, z}] (* A203430 *) Table[v[n+1]/v[n], {n, z}] (* this sequence *) Table[v[n]/d[n], {n, z}] (* A203432 *) PROG (Magma) A203431:= func< n | n eq 1 select 2 else (&*[n-j+Floor((n+1)/2)-Floor((j+1)/2): j in [0..n-1]]) >; [A203431(n): n in [1..25]]; // G. C. Greubel, Sep 27 2023 (SageMath) def A203431(n): return product(n-j+((n+1)//2)-((j+1)//2) for j in range(n)) [A203431(n) for n in range(1, 31)] # G. C. Greubel, Sep 27 2023 CROSSREFS Cf. A032766, A203430, A203432. Sequence in context: A095927 A296248 A325506 * A137981 A110351 A326224 Adjacent sequences: A203428 A203429 A203430 * A203432 A203433 A203434 KEYWORD nonn AUTHOR Clark Kimberling, Jan 02 2012 STATUS approved

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Last modified May 24 14:39 EDT 2024. Contains 372778 sequences. (Running on oeis4.)