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a(n) = ((2n)^((2n+1)^2) + 1)/(2n+1)^3.
1

%I #6 Jun 07 2021 04:42:07

%S 1,19,9007199254741,392750863685502459010271914701912679,

%T 19389268200585836264288587113776883575610248525384021488302948711030121,

%U 7513148009015777610818933132982719759579263711495116453794139744552967693463561232156273478587528174305033809166040571

%N a(n) = ((2n)^((2n+1)^2) + 1)/(2n+1)^3.

%F a(n) = ((2n)^((2n+1)^2) + 1)/(2n+1)^3.

%t Table[ ((2n)^((2n+1)^2) + 1)/(2n+1)^3, {n, 0, 10} ]

%Y Cf. A137641 (((n-1)^(n^2) + 1)/n^3).

%Y Cf. A137642 (((p+1)^(p^2) - 1)/p^3 where p = prime(n)).

%Y Cf. A133591 (((p-1)^(p^2) + 1)/p^3 where p = prime(n)).

%K nonn

%O 0,2

%A _Alexander Adamchuk_, Jan 31 2008