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%I #14 Oct 19 2023 07:37:28
%S 0,0,0,1,1,1,1,2,1,3,0,3,1,3,2,4,0,4,1,6,2,3,0,7,2,4,1,6,0,8,1,6,1,4,
%T 2,10,0,3,2,10,0,9,1,7,4,4,0,14,2,8,0,8,0,9,2,10,1,4,0,18,1,4,4,11,2,
%U 11,0,7,1,11,0,20,1,5,4,9,1,13,0,16,2,5,0,21,2,6,0,12,0,21,3,9,1,5,2,23,0,7
%N Numbers of prime pairs (p,q), p<=q, such that (p+q) divides n.
%H Robert Israel, <a href="/A079055/b079055.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = Sum_{d|n} A061358(d). - _Robert Israel_, Oct 17 2023
%p N:= 100: # for a(1)..a(N)
%p P:= select(isprime,[2,seq(i,i=3..N,2)]): nP:= nops(P):
%p V:= Vector(N):
%p for i from 1 to nP do
%p for j from i to nP do
%p v:= P[i]+P[j];
%p J:= [seq(t,t=v..N,v)];
%p V[J]:= V[J] +~ 1
%p od od:
%p convert(V,list); # _Robert Israel_, Oct 17 2023
%o (PARI) a(n)=sum(i=1,n,sum(j=1,i,if(n%(prime(i)+prime(j)),0,1)))
%Y Cf. A061358.
%K nonn,look
%O 1,8
%A _Benoit Cloitre_, Feb 02 2003
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