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 A166021 #2 Mar 31 2012 13:21:19 %S A166021 2,4,5,8,9,10,14,15,16,17,22,23,24,25,26,32,33,34,35,36,37,44,45,46, %T A166021 47,48,49,50,58,59,60,61,62,63,64,65,74,75,76,77,78,79,80,81,82,92,93, %U A166021 94,95,96,97,98,99,100,101,112,113,114,115,116,117,118,119,120,121 %N A166021 a(n) = 2*A000124(A003056(n-1)) if A002262(n-1)=0, otherwise a(n-1)+1. %o A166021 (MIT Scheme:) (define (A166021 n) (if (zero? (A002262 (-1+ n))) (* 2 (A000124 (A003056 (-1+ n)))) (1+ (A166021 (-1+ n))))) %Y A166021 Complement of A136272. %K A166021 nonn,tabl,easy %O A166021 1,1 %A A166021 _Antti Karttunen_, Oct 05 2009