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 A303269 #6 May 18 2018 19:47:24 %S A303269 0,1,-4,9,-16,25,-36,49,-64,81,1,2,-3,10,-15,26,-35,50,-63,82,-4,-3, %T A303269 -8,5,-20,21,-40,45,-68,77,9,10,5,18,-7,34,-27,58,-55,90,-16,-15,-20, %U A303269 -7,-32,9,-52,33,-80,65,25,26,21,34,9,50,-11,74,-39,106,-36,-35,-40,-27 %N A303269 Sum of squares of odd digits minus sum of squares of even digits of n. %C A303269 Up to 10^4, resp. 10^5, there are 5824, resp. 59316, positive terms. All terms from a(1) to a(11111) are nonzero: see A076164 for indices of zeros. %o A303269 (PARI) A303269(n)=-vecsum(apply(d->d^2*(-1)^d,digits(n))) %Y A303269 Cf. A076164, A071650, A036301. %K A303269 sign,base %O A303269 0,3 %A A303269 _M. F. Hasler_, May 18 2018