This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A281375 #9 Jan 20 2017 20:33:58 %S A281375 4,4,5,8,12,21,36,64,113,204,372,682,1260,2340,4369,8192,15420,29127, %T A281375 55188,104857,199728,381300,729444,1398101,2684354,5162220,9942053, %U A281375 19173961,37025580,71582788,138547332,268435456,520602096,1010580540,1963413621,3817748707,7429132620,14467258260,28192605840,54975581388 %N A281375 a(n) = floor(2^(n+1)/n). %H A281375 Robert Israel, <a href="/A281375/b281375.txt">Table of n, a(n) for n = 1..3329</a> %F A281375 a(n) = A053639(n) if n is in A000079, otherwise A053639(n)-1. %F A281375 a(2k-1) = A191636(k) for k > 1. %F A281375 a(n) = (2^(n+1)-A112983(n))/n. %p A281375 seq(floor(2^(n+1)/n), n=1..50); # _Robert Israel_, Jan 20 2017 %o A281375 (PARI) a(n) = 2^(n+1)\n \\ _Felix Fröhlich_, Jan 20 2017 %Y A281375 Cf. A053639, A112983, A191636. %K A281375 nonn,easy %O A281375 1,1 %A A281375 _Robert Israel_, Jan 20 2017