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%I #22 May 03 2017 07:54:39
%S 1,2,0,1,2,1,1,2,0,1,1,2,1,0,1,1,1,1,2,0,1,2,2,0,1,2,0,1,1,1,1,0,1,1,
%T 2,1,0,2,1,2,1,0,1,1,0,2,2,1,1,1,0,1,1,1,2,1,1,0,1,1,2,1,1,1,0,2,1,1,
%U 1,2,0,0,2,0,1,1,2,1,0,1,2,1,1,1,1,1,1,2,0,1,1,1,1,1,0,0,1,3
%N Number of distinct prime divisors p of the n-th composite number c such that gpf(c - p) = p, where gpf = greatest prime factor (A006530).
%C a(n) gives the number of times that the n-th composite number occurs in A070229.
%H Robert Israel, <a href="/A260648/b260648.txt">Table of n, a(n) for n = 1..10000</a>
%e a(8) = 2 since the distinct prime divisors of A002808(8) = 15 are 3 and 5, A006530(15 - 3) = 3 and A006530(15 - 5) = 5, so all prime 3 and 5 are to be considered.
%p N:= 1000: # to consider composites <= N
%p f:= proc(c) local p, t;
%p if isprime(c) then return NULL fi;
%p nops(select(p -> max(numtheory:-factorset(c/p-1))<=p, numtheory:-factorset(c)))
%p end proc:
%p map(f, [$4..N]); # _Robert Israel_, May 02 2017
%Y Cf. A002808 (composite), A006530 (gpf).
%K nonn
%O 1,2
%A _Gionata Neri_, Nov 12 2015
%E a(87) corrected by _Robert Israel_, May 02 2017
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