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 A184896 a(n) = C(2n,n) * (7^n/n!^2) * Product_{k=0..n-1} (7k+1)*(7k+6). 6
 1, 84, 45864, 35672000, 32445913500, 32247604076688, 33935228690034672, 37165308416775931392, 41919854708375196052500, 48365506771435816732770000, 56812832722107710740048677120, 67715433011522917282547695380480 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS FORMULA Self-convolution of A184895, where A184895(n) = (7^n/n!^2) * Product_{k=0..n-1} (14k+1)*(14k+6). a(n) ~ sin(Pi/7) * 2^(2*n) * 7^(3*n) / (Pi*n)^(3/2). - Vaclav Kotesovec, Oct 23 2020 EXAMPLE G.f.: A(x) = 1 + 84*x + 45864*x^2 + 35672000*x^3 +... A(x)^(1/2) = 1 + 42*x + 22050*x^2 + 16909900*x^3 +...+ A184895(n)*x^n +... PROG (PARI) {a(n)=(2*n)!/n!^2*(7^n/n!^2)*prod(k=0, n-1, (7*k+1)*(7*k+6))} CROSSREFS Cf. A184895; variants: A184423, A008977, A184892, A001421, A184898. Sequence in context: A184126 A185403 A269897 * A203093 A290274 A289557 Adjacent sequences: A184893 A184894 A184895 * A184897 A184898 A184899 KEYWORD nonn AUTHOR Paul D. Hanna, Jan 25 2011 STATUS approved

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Last modified March 28 01:22 EDT 2023. Contains 361575 sequences. (Running on oeis4.)