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 A081303 #3 Mar 30 2012 18:50:31 %S A081303 -1,-2,-3,-2,-5,-1,-7,-2,-3,1,-11,-1,-13,3,-1,-2,-17,-1,-19,1,1,7,-23, %T A081303 -1,-5,9,-3,3,-29,1,-31,-2,5,13,-3,-1,-37,15,7,1,-41,3,-43,7,-1,19, %U A081303 -47,-1,-7,1,11,9,-53,-1,1,3,13,25,-59,1,-61,27,1,-2,3,7,-67,13,17,3,-71,-1,-73,33,-1,15 %N A081303 gpf(m) - 2*spf(m), where gpf(m) is the greatest and spf(m) is the smallest prime factor of m (A006530, A020639). %Y A081303 Cf. A046665, A081304, A081305, A081306, A069900. %K A081303 sign %O A081303 1,2 %A A081303 _Reinhard Zumkeller_, Mar 17 2003