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 A136411 a(n) = Product_{k=1..n} (2*k-1)^(2*n-2*k+1). 2
 1, 3, 135, 212625, 21097715625, 207248662456171875, 291128066470548703880859375, 79746389028864195813528714933837890625, 5570294521107277357810167397301815834831695556640625 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS G. C. Greubel, Table of n, a(n) for n = 1..29 FORMULA a(n) = A107254(n) / 2^(n*(n - 1)). a(n) = sf(2*n-1) / (2^(n*(n-1)) * sf(n-1)^2), n >= 1, where sf(n) = BarnesG(n + 2) is the superfactorial defined in A000178. - Robert Coquereaux, Apr 02 2013 a(n) ~ A * 2^(n^2 + n - 1/12) * n^(n^2 + 1/12) / exp(3*n^2/2 + 1/12), where A = A074962 = 1.2824271291... is the Glaisher-Kinkelin constant. - Vaclav Kotesovec, Jul 10 2015 MATHEMATICA Table[Product[(2*k - 1)^(2*n - 2*k + 1), {k, 1, n}], {n, 1, 10}] (* Stefan Steinerberger, May 18 2008 *) sf[n_] := BarnesG[n + 2]; a[n_] := sf[2 n - 1]/(2^(n (n - 1)) sf[n - 1]^2); Table[a[n], {n, 1, 10}]  (* Robert Coquereaux, Apr 02 2013 *) PROG (PARI) a(n) = prod(k=1, n, (2*k-1)^(2*n-2*k+1)) \\ Anders HellstrÃ¶m, Sep 16 2015 (MAGMA) [(&*[(2*k-1)^(2*n-2*k+1): k in [1..n]]): n in [1..10]]; // G. C. Greubel, Oct 14 2018 CROSSREFS Cf. A136807, A087315, A000178, A055209. Sequence in context: A173582 A065973 A110973 * A193136 A037120 A082923 Adjacent sequences:  A136408 A136409 A136410 * A136412 A136413 A136414 KEYWORD easy,nonn AUTHOR Ctibor O. Zizka, Mar 31 2008 EXTENSIONS More terms from Stefan Steinerberger, May 18 2008 STATUS approved

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Last modified January 23 07:07 EST 2020. Contains 331168 sequences. (Running on oeis4.)