A053639 a(n) = ceiling(2^(n+1)/n).

4, 4, 6, 8, 13, 22, 37, 64, 114, 205, 373, 683, 1261, 2341, 4370, 8192, 15421, 29128, 55189, 104858, 199729, 381301, 729445, 1398102, 2684355, 5162221, 9942054, 19173962, 37025581, 71582789, 138547333, 268435456, 520602097

Offset: 1

Author

N. J. A. Sloane, Mar 23 2000

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A053637, A053638.

Programs

Magma

[Ceiling(2^(n+1)/n): n in [1..40]]; // Vincenzo Librandi, Dec 19 2011

Maple

A053639:=n->ceil(2^(n+1)/n): seq(A053639(n), n=1..40); # Wesley Ivan Hurt, Jan 19 2017

Mathematica

Table[Ceiling[2^(n+1)/n],{n,1,40}] (* Vincenzo Librandi, Dec 19 2011 *)

PARI

vector(40, n, ceil(2^(n+1)/n) ) \\ G. C. Greubel, May 17 2019

Sage

[ceil(2^(n+1)/n) for n in (1..40)] # G. C. Greubel, May 17 2019