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%I #3 Mar 30 2012 18:50:19
%S 1,3,5,7,9,11,14,16,19,23,27,31,35,38,42,47,52,56,61,65,70,76,82,88,
%T 94,100,107,114,121,128,136,143,150,158,166,175,185,194,203,213,223,
%U 233,243,252,262,272,282,291,301,311,322,334,346
%N a(n) = #{(x,y) | 0<=y<=x<=n and x+y is prime}.
%F a(0) = 0, for n>0: a(n) = a(n-1) + A035250(n).
%e a(3)=5, as sums of (1,1), (2,0), (2,1), (3,0) and (3,2) give 5 primes.
%Y Cf. A000720, A035250.
%K nonn
%O 0,2
%A _Reinhard Zumkeller_, Jan 07 2002
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