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A280100
a(n) = 4^(2*n) * (n!)^3 * (n+1)!.
2
1, 32, 12288, 21233664, 108716359680, 1304596316160000, 31560794080542720000, 1385645103312147578880000, 102160842176998016695664640000, 11916040631525048667382323609600000, 2097223151148408565459288955289600000000
OFFSET
0,2
LINKS
FORMULA
a(n) ~ Pi/4 * A134374(n).
a(n) ~ Pi^2 * 2^(4*n+2) / exp(4*n+1) * n^(3*n+3/2) * (n+1)^(n+3/2).
Lim_{n->infinity} a(n) / ((2n+1)!)^2 = Pi/4.
a(n) / ((2n+1)!)^2 = A278145(n) / A161736(n+2).
PROG
(PARI) a(n) = 4^(2*n) * (n!)^3 * (n+1)!;
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Daniel Suteu, Dec 25 2016
STATUS
approved