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 A289623 #10 Jul 19 2017 20:10:27 %S A289623 0,1,2,3,1,1,1,1,6,5,4,9,2,7,1,13,1,1,1,1,1,1,2,1,3,1,2,1,1,16,8,1,2, %T A289623 10,2,30,2,3,14,3,1,23,1,17,1,1,2,4,18,1,1,4,1,1,1,35,1,15,11,1,1,1,1, %U A289623 3,1,1,1,1,21,1,12,1,1,1,2,1,1,1,1,1,65,3,2,1,19,20,1,1,4,56,1,32,2,1,2,1,2,1,38,6 %N A289623 a(n) = A055396(A048673(n)). %C A289623 From the scatter plot it can be seen that the terms are grouped into two distinct populations by their magnitude, with significant gap between them. %H A289623 Antti Karttunen, <a href="/A289623/b289623.txt">Table of n, a(n) for n = 1..16384</a> %F A289623 a(n) = A055396(A048673(n)). %o A289623 (PARI) %o A289623 A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ This function from _Michel Marcus_ %o A289623 A048673(n) = (A003961(n)+1)/2; %o A289623 A055396(n) = if(n==1, 0, primepi(factor(n)[1, 1])); \\ This function from _Charles R Greathouse IV_, Apr 23 2015 %o A289623 A289623(n) = A055396(A048673(n)); %Y A289623 Cf. A048673, A055396, A246263 (the positions of ones). %Y A289623 Cf. also A278224, A286582, A286583, A286584, A286586. %K A289623 nonn,look %O A289623 1,3 %A A289623 _Antti Karttunen_, Jul 16 2017