A281375 a(n) = floor(2^(n+1)/n).

4, 4, 5, 8, 12, 21, 36, 64, 113, 204, 372, 682, 1260, 2340, 4369, 8192, 15420, 29127, 55188, 104857, 199728, 381300, 729444, 1398101, 2684354, 5162220, 9942053, 19173961, 37025580, 71582788, 138547332, 268435456, 520602096, 1010580540, 1963413621, 3817748707, 7429132620, 14467258260, 28192605840, 54975581388

Offset: 1

Author

Robert Israel, Jan 20 2017

Keywords

• nonn
• easy

Links

• Robert Israel, Table of n, a(n) for n = 1..3329

Crossrefs

Cf. A053639, A112983, A191636.

Programs

Maple

seq(floor(2^(n+1)/n), n=1..50); # Robert Israel, Jan 20 2017

PARI

a(n) = 2^(n+1)\n \\ Felix Fröhlich, Jan 20 2017

Formula

a(n) = A053639(n) if n is in A000079, otherwise A053639(n)-1.

a(2k-1) = A191636(k) for k > 1.

a(n) = (2^(n+1)-A112983(n))/n.