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%I #3 Feb 14 2022 22:43:25
%S 1,2,1,3,1,4,1,3,1,4,1,7,1,2,1,4,1,6,1,5,1,4,1,8,1,2,1,5,1,10,1,4,1,3,
%T 1,11,1,2,1,7,1,8,1,5,1,3,1,10,1,4,1,5,1,7,1,5,1,4,1,17,1,2,1,4,1,8,1,
%U 4,1,8,1,14,1,2,1,4,1,8,1,8,1,4,1,15,1,2,1,7,1,15
%N Number of pairs of divisors of n, (d1,d2) d1<=d2, such that d1+d2 is prime.
%F a(n) = Sum_{d1|n, d2|n, d1<=d2} c(d1 + d2), where c is the prime characteristic (A010051).
%e a(12) = 7; The pairs are (1,1), (1,2), (1,4), (1,6), (1,12), (2,3), (3,4).
%Y Cf. A010051.
%K nonn
%O 1,2
%A _Wesley Ivan Hurt_, Feb 14 2022
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