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A260982 a(n) = (2^(2^(n+1)) + 2^(2^n) + 1)/21. 0

%I #32 Sep 08 2022 08:46:13

%S 1,13,3133,204525373,878416384666881853,

%T 16203922234330403022943873881213226813,

%U 5513909011300771210646237381366090850171917477741023928710521838825947516733

%N a(n) = (2^(2^(n+1)) + 2^(2^n) + 1)/21.

%F a(n) = A001576(2^n)/21. - _Michel Marcus_, Aug 14 2015

%e a(2) = (2^(2^(2+1)) + 2^(2^2) + 1)/21 = 13.

%t Table[(2^(2^(n + 1)) + 2^(2^n) + 1)/21, {n, 1, 10}] (* _Vincenzo Librandi_, Aug 08 2015 *)

%o (PARI) first(m)=my(v=vector(m,t,(2^(2^(t+1))+2^(2^t)+1)/21));v; /* _Anders Hellström_, Aug 07 2015 */

%o (Magma) [(2^(2^(n+1)) + 2^(2^n) + 1)/21: n in [1..10]]; // _Vincenzo Librandi_, Aug 08 2015

%Y Cf. A001576 (1^n + 2^n + 4^n).

%K nonn,easy

%O 1,2

%A _Marco RipĂ _, Aug 07 2015

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Last modified March 28 10:55 EDT 2024. Contains 371241 sequences. (Running on oeis4.)