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A222621 a(n) = (2n-1)^(2n). 3

%I #38 Sep 08 2022 08:46:04

%S 1,81,15625,5764801,3486784401,3138428376721,3937376385699289,

%T 6568408355712890625,14063084452067724991009,

%U 37589973457545958193355601,122694327386105632949003612841,480250763996501976790165756943041,2220446049250313080847263336181640625

%N a(n) = (2n-1)^(2n).

%H Vincenzo Librandi, <a href="/A222621/b222621.txt">Table of n, a(n) for n = 1..190</a>

%F a(n) = A005408(n-1)^A005843(n). - _Michel Marcus_, Apr 14 2018

%F Sum_{n>=1} 1/a(n) = A338168. - _Amiram Eldar_, Nov 29 2020

%e 1^2; 3^4; 5^6; 7^8 and so on.

%t Table[(2 n - 1)^(2 n), {n, 20}] (* _T. D. Noe_, Feb 26 2013 *)

%o (Magma) [(2*n - 1)^(2*n): n in [1..13]]; // _Vincenzo Librandi_, Feb 26 2013

%o (PARI) a(n)=(2*n-1)^(2*n) \\ _Charles R Greathouse IV_, Aug 20 2013

%Y Cf. A005408, A005843, A085535, A338168.

%K nonn,easy

%O 1,2

%A _Dave Durgin_, Feb 26 2013

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Last modified March 28 08:12 EDT 2024. Contains 371236 sequences. (Running on oeis4.)