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 A257259 #7 May 13 2015 15:33:58 %S A257259 1,-1,0,-1,-1,-3,-1,-6,-8,-10,-7,-4,2,2,-14,-90,-318,-896,-2166,-4691, %T A257259 -9298,-17175,-30007,-50261,-81664,-129637,-200973,-301205,-426500, %U A257259 -545183,-561511,-252122,836543,3542930,9312475,20508985,40858087,76119037,135203839,232236417,390709345,652711050,1101492173,1921013671,3558812217,7170401227,15800043812,37400877416 %N A257259 a(n) = A218542(n) - A218543(n). %C A257259 a(n) = the difference between the number of even and odd numbers encountered when traversing from 2^(n+1)-1 to (2^n)-1 by iterating the map A011371: x -> x - (number of 1's in binary representation of x). %F A257259 a(n) = A218542(n) - A218543(n). %o A257259 (Scheme) (define (A257259 n) (- (A218542 n) (A218543 n))) %Y A257259 Cf. A011371, A218542, A218543, A213709. %Y A257259 Partial sums: A257805. %K A257259 sign %O A257259 0,6 %A A257259 _Antti Karttunen_, May 13 2015