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 A297109 #10 Dec 26 2017 17:33:38 %S A297109 0,1,2,1,3,0,4,1,2,0,5,0,6,0,0,1,7,0,8,0,0,0,9,0,3,0,2,0,10,0,11,1,0, %T A297109 0,0,0,12,0,0,0,13,0,14,0,0,0,15,0,4,0,0,0,16,0,0,0,0,0,17,0,18,0,0,1, %U A297109 0,0,19,0,0,0,20,0,21,0,0,0,0,0,22,0,2,0,23,0,0,0,0,0,24,0,0,0,0,0,0,0,25,0,0,0,26,0,27,0,0 %N A297109 If n is prime(k)^e, e >= 1, then a(n) = k, otherwise 0. %H A297109 Antti Karttunen, <a href="/A297109/b297109.txt">Table of n, a(n) for n = 1..65537</a> %F A297109 If A001221(n) = 1 [when n is in A000961], then a(n) = A055396(n) = A001511(A297108(n)), otherwise 0. %o A297109 (PARI) A297109(n) = if(1==omega(n),primepi(factor(n)[1,1]),0); %Y A297109 Cf. A000720, A000961, A001221, A001511, A055396, A100995, A297108. %K A297109 nonn %O A297109 1,3 %A A297109 _Antti Karttunen_, Dec 25 2017