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 A354527 #18 Aug 17 2022 05:07:40 %S A354527 0,0,0,1,0,0,0,1,0,1,0,2,0,0,0,1,0,2,0,1,0,1,0,1,0,1,1,1,0,2,0,1,0,1, %T A354527 0,2,0,1,1,1,0,2,0,1,0,1,0,2,0,2,0,1,0,2,0,1,1,1,0,3,0,0,1,1,1,2,0,1, %U A354527 0,2,0,2,0,1,1,1,0,1,0,2,1,1,0,3,0,1,1,1,0,3,0 %N A354527 a(n) = A001221(n) - A354512(n). %C A354527 Number of distinct prime factors p of n such that gpf(n+p) != p, gpf = A006530. %C A354527 Number of distinct prime factors p of n such that n+p is not p-smooth. %H A354527 Jianing Song, <a href="/A354527/b354527.txt">Table of n, a(n) for n = 1..10000</a> %e A354527 a(30) = 2 since the prime factors of 30 are 2,3,5, and we have gpf(30+3) != 3 and gpf(30+5) != 5. %o A354527 (PARI) gpf(n) = vecmax(factor(n)[, 1]); %o A354527 a(n) = my(f=factor(n)[, 1]); sum(i=1, #f, gpf(n+f[i])!=f[i]) %Y A354527 Cf. A001221, A354512, A006530. %Y A354527 Cf. A354525 (indices of 0), A354526 (indices of positive terms). %K A354527 nonn,easy %O A354527 1,12 %A A354527 _Jianing Song_, Aug 16 2022