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A349113
a(n) = 8^n * P(3*n, n), where P(n, x) is n-th Legendre polynomial.
2
1, 8, 40636, 748832256, 37759888297756, 4086692369433395200, 815254385427670754825764, 270587150855247020644760551424, 138859707622050969870951620062449436, 104286590422721059977069662227099300134912, 109828573459404650800550127862919905133973562480
OFFSET
0,2
COMMENTS
In general, for k>=1, P(k*n, n) ~ 2^(k*n) * n^(k*n) / sqrt(k*Pi*n).
LINKS
Eric Weisstein's World of Mathematics, Legendre Polynomial.
FORMULA
a(n) ~ 2^(6*n) * n^(3*n - 1/2) / sqrt(3*Pi).
MATHEMATICA
Table[8^n*LegendreP[3*n, n], {n, 0, 12}]
PROG
(PARI) a(n) = 8^n*pollegendre(3*n, n); \\ Michel Marcus, Nov 08 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Nov 08 2021
STATUS
approved