A191640 a(n) = floor((-1 + 4^n)/(-1 + 4*n)).

1, 2, 5, 17, 53, 178, 606, 2114, 7489, 26886, 97541, 356962, 1315860, 4880644, 18199013, 68174084, 256415957, 967879954, 3665038759, 13917868706, 52988512181, 202209034993, 773282903051, 2962894491691, 11372726331743, 43724268226898, 168358864574597

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Mathematica

f[n_] := Floor[(-1+4^n)/(-1+4 n)]
Table[f[n], {n, 1, 40}]     (* A191640 *)

Prog

(Magma) [Floor((-1+4^n)/(-1+4*n)): n in [1..30] ]; // Vincenzo Librandi, Sep 10 2011
(Maxima) A191640(n):=floor((-1+4^n)/(-1+4*n))$ makelist(A191640(n), n, 1, 30); /* Martin Ettl, Oct 25 2012 */

Crossrefs

Cf. A191641.

Sequence in context: A141303 A263678 A133510 * A148408 A002692 A148409

Adjacent sequences: A191637 A191638 A191639 * A191641 A191642 A191643

Keyword

nonn

Author

Clark Kimberling, Jun 09 2011

Status

approved