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 A145015 #2 Jun 01 2010 03:00:00 %S A145015 1,3,1,3,3,5,3,1,1,3,1,7,7,1,3,5,3,13,7,1,3,1,1,3,3,1,1,3,1,7,3,1,1,3, %T A145015 1,7,1,15,15,1,7,1,3,5,7,1,3,5,3,13,7,1,3,5,3,13,3,29,15,1,7,1,3,1,1, %U A145015 3,7,1,3,1,1,3,3,1,1,3,1,7,7,1,3,1,1,3,3,1,1,3,1,7,3,1,1,3,1,7,1,15,7,1 %N A145015 Run lengths in A037861 having the same sign. %C A145015 a(n) seems (conjecture) to contain only the numbers 2^n - 1 (for n>=1) and 2^n - 3 (for n>=3) %e A145015 A037861 is: 1,-1,0,-2,1,-1,-1,-3,2,0,0,-2,0,-2,-2,-4,3, ... so sign is +,-,0,-,+,-,-,-,+,0,0,-,0,-,-,-,+, ... thus sequence is 1,3,1,3,3,5, ... %Y A145015 Cf. A037861. %K A145015 base,nonn %O A145015 0,2 %A A145015 Denis Boigelot (dboigelo(AT)ulb.ac.be), Sep 29 2008