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 A141553 #4 Mar 30 2012 18:52:27 %S A141553 0,0,4,9,6,15,12,0,9,18,20,27,12,18,33,12,30,27,0,36,45,30,18,51,44, %T A141553 36,45,54,36,63,24,40,45,60,66,27,54,60,68,81,54,87,60,0,66,81,90,84, %U A141553 75,36,105,60,102,72,99,72,36,117,90,90,123,108,108,81,88,126,116,135,102,48 %N A141553 Transformed nonprime products of prime factors of the composites, the largest prime decremented by 2 and the smallest prime incremented by 1. %C A141553 In the prime number decomposition of k=A002808(i), i=1,2,3,.., one instance of the largest prime, pmax=A052369(i), is replaced by pmax-2 and one instance of the smallest prime, pmin=A056608(i), is replaced by pmin+1. If the product of this modified list of factors, k*(pmax-2)*(pmin+1)/(pmin*pmax), is nonprime, it is added to the sequence. %e A141553 k(1)=(p(max)=2)*(p(min)=2), transformed (2-2)*(2+1)=0*3=0=a(1). %e A141553 k(2)=(p(max)=3)*(p(min)=2), transformed (3-2)*(2+1)=1*3=3 (prime, skipped). %e A141553 k(3)=(p(max)=2)*(p=2)*(p(min)=2), transformed (2-2)*2*(2+1)=0*2*3=0=a(2), etc. %Y A141553 Cf. A141218, A141219, A141220, A141284. %K A141553 nonn %O A141553 1,3 %A A141553 _Juri-Stepan Gerasimov_, Aug 14 2008 %E A141553 Edited and corrected by _R. J. Mathar_, Aug 18 2008