cp's OEIS Frontend

A319679 Number of distinct prime signatures that occur when map x -> A268674(x) is iterated, starting from x = n, until an even number is reached; a(1) = 0 by convention.

%I A319679 #8 Nov 21 2018 09:23:41
%S A319679 0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,2,1,1,1,1,1,2,1,
%T A319679 1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,2,1,1,1,2,1,2,1,1,1,1,1,2,1,2,1,1,1,
%U A319679 2,1,1,1,1,1,2,1,1,1,1,1,2,1,1,1,2,1,2,1,1,1,2,1,2,1,1,1,1,1,2,1,1,1,1,1,2
%N A319679 Number of distinct prime signatures that occur when map x -> A268674(x) is iterated, starting from x = n, until an even number is reached; a(1) = 0 by convention.
%C A319679 Number of distinct values that A046523 obtains when applied to n and all the terms above it in that column where it is located in array A083221.
%H A319679 Antti Karttunen, <a href="/A319679/b319679.txt">Table of n, a(n) for n = 1..32769</a>
%o A319679 (PARI)
%o A319679 up_to = 32769;
%o A319679 v268674 = readvec("./b268674_terms_only-32769.txt"); \\ Prepared from the b-file of A268674.
%o A319679 A268674(n) = v268674[n];
%o A319679 A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); }; \\ From A046523
%o A319679 A319679(n) = if(1==n,0,my(m=Map(),s,k=0); while(1,if(!mapisdefined(m,s=A046523(n)), mapput(m,s,s); k++); if(!(n%2), return(k)); n = A268674(n)));
%Y A319679 Cf. A046523, A083221, A268674.
%Y A319679 Cf. also A319689.
%K A319679 nonn
%O A319679 1,21
%A A319679 _Antti Karttunen_, Nov 20 2018