A217994 a(n) = 2^((2 + n + n^2)/2).

2, 4, 16, 128, 2048, 65536, 4194304, 536870912, 137438953472, 70368744177664, 72057594037927936, 147573952589676412928, 604462909807314587353088

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..80

Formula

a(n) = a(n-1)*(2^n), with a(0)=2.

G.f.: G(0)/x -1/x, where G(k)= 1 + 2^k*x/(1 - x/(x + x/G(k+1) )); (continued fraction). - Sergei N. Gladkovskii, Jul 26 2013

Example

a(3) = 128 because a(3) = 2^(2 + 3 + 3^2)/2 = 2^14/2 = 2^7 = 128.

Mathematica

Table[2^((2 + n + n^2) / 2), {n, 0, 30}] (* Vincenzo Librandi, Jul 26 2013 *)

Prog

(Maxima) A217994[n]:=2^((2+n+n^2)/2)$
makelist(A217994[n], n, 0, 30); /* Martin Ettl, Oct 29 2012 */
(PARI) a(n)=2<<((n+n^2)/2) \\ Charles R Greathouse IV, Jan 06 2013
(Magma) [2^((2 + n + n^2) div  2): n in [0..15]]; // Vincenzo Librandi, Jul 26 2013

Crossrefs

Sequence in context: A009200 A144526 A179532 * A174677 A073924 A362065

Adjacent sequences: A217991 A217992 A217993 * A217995 A217996 A217997

Keyword

nonn,easy

Author

Mokhtar Mohamed, Oct 19 2012

Status

approved