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A216702 a(n) = Product_{k=1..n} (16 - 4/k).

%I A216702 #39 Aug 17 2025 01:25:10
%S A216702 1,12,168,2464,36960,561792,8614144,132903936,2060011008,32044615680,
%T A216702 499896004608,7816555708416,122459372765184,1921670157238272,
%U A216702 30197673899458560,475110069351481344,7482983592285831168,117967035454858985472,1861257670509997326336
%N A216702 a(n) = Product_{k=1..n} (16 - 4/k).
%C A216702 This sequence is generalizable: Product_{k=1..n} (q^2 - q/k) = (q^n/n!) * Product_{k=0..n-1} (q*k + q-1) = expansion of (1- x*q^2)^((1-q)/q).
%H A216702 Harvey P. Dale, <a href="/A216702/b216702.txt">Table of n, a(n) for n = 0..800</a>
%F A216702 G.f.: 1/(1-16*x)^(3/4). - _Harvey P. Dale_, Sep 19 2012
%F A216702 From _Peter Bala_, Sep 24 2023: (Start)
%F A216702 a(n) = 16^n * binomial(n - 1/4, n).
%F A216702 P-recursive: a(n) = 4*(4*n - 1)/n * a(n-1) with a(0) = 1. (End)
%F A216702 From _Peter Bala_, Mar 31 2024: (Start)
%F A216702 a(n) = (-16)^n * binomial(-3/4, n).
%F A216702 a(n) ~ 1/Gamma(3/4) * 16^n/n^(1/4).
%F A216702 E.g.f.: hypergeom([3/4], [1], 16*x).
%F A216702 a(n) = (16^n)*Sum_{k = 0..2*n} (-1)^k*binomial(-3/4, k)* binomial(-3/4, 2*n - k).
%F A216702 (16^n)*a(n) = Sum_{k = 0..2*n} (-1)^k*a(k)*a(2*n-k).
%F A216702 Sum_{k = 0..n} a(k)*a(n-k) = (16^n)/(2*n)! * Product_{k = 1..n} (4*k^2 - 1) =  (16^n)/(2*n)! * A079484(n). (End)
%p A216702 seq(product(16-4/k, k=1.. n), n=0..20);
%p A216702 seq((4^n/n!)*product(4*k+3, k=0.. n-1), n=0..20);
%t A216702 Table[Product[16-4/k,{k,n}],{n,0,20}] (* or *) CoefficientList[ Series[ 1/(1-16*x)^(3/4),{x,0,20}],x] (* _Harvey P. Dale_, Sep 19 2012 *)
%Y A216702 Cf. A004988, A049382, A004994, A034385, A098430.
%K A216702 nonn,easy
%O A216702 0,2
%A A216702 _Michel Lagneau_, Sep 16 2012