A015486 a(0)=1, a(1)=2, a(n) = sum_{k=0}^{k=n-1} 2^k a(k).

1, 2, 5, 25, 225, 3825, 126225, 8204625, 1058396625, 272007932625, 139540069436625, 143028571172540625, 293065542332535740625, 1200689526936398929340625, 9837249294189916428087740625, 161183329685301780674217630140625

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..70

Prog

(Magma) I:=[1, 2, 5]; [n le 3 select I[n] else (2^(n-2)+1)*Self(n-1): n in [1..18]]; // Vincenzo Librandi, Nov 10 2012

Crossrefs

Sequence in context: A049650 A191506 A139007 * A378327 A191951 A356674

Adjacent sequences: A015483 A015484 A015485 * A015487 A015488 A015489

Keyword

nonn,easy

Author

Olivier Gérard

Status

approved