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 A064922 #9 Jun 21 2018 02:01:35 %S A064922 0,0,1,0,2,0,1,1,3,0,3,0,2,1,2,0,2,0,2,2,4,0,4,2,3,1,4,0,4,0,1,1,3,1, %T A064922 3,0,3,2,4,0,4,0,3,1,5,0,3,1,3,1,3,0,3,2,3,3,5,0,3,0,2,2,2,1,3,0,3,3, %U A064922 3,0,4,0,4,1,5,1,3,0,3,1,5,0,3,3,4,1,3,0,5,1,4,2,4,1,4,0,3,1,5,0,5,0,3,3,4 %N A064922 Number of iterations in A064920 to reach a prime. %C A064922 a(p) = 0 for all primes p. %H A064922 Harry J. Smith, <a href="/A064922/b064922.txt">Table of n, a(n) for n = 2..1000</a> %e A064922 a(18) = 2 as A064920(A064920(18)) = A064920(8) = 5 = A064921(18). %o A064922 (PARI) gpf(n)= { local(f); f=factor(n)~; return(f[1, length(f)]) } { for (n=2, 1000, m=n; a=0; while (!isprime(m), g=gpf(m); m=m / g + g - 1; a++); write("b064922.txt", n, " ", a) ) } \\ _Harry J. Smith_, Sep 29 2009 %Y A064922 Cf. A064920, A064921, A064918. %K A064922 nonn %O A064922 2,5 %A A064922 _Reinhard Zumkeller_, Oct 14 2001