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%I #23 Nov 28 2015 19:16:15
%S 1,2,3,4,6,7,9,11,12,14,15,21,25,29,35,55,58,59,64,71,85,89,93,94,95,
%T 100,101,102,108,112,114,116,122,124,130,131,133,135,141,146,147,151,
%U 159,162,165,170,171,172,177,178,183,190,192,193,194,204,205,206
%N Integers n such that A007504(n) is the sum of 2 nonzero squares.
%C Integers n such that sum of the first n primes is the sum of 2 nonzero squares.
%C Initial values of corresponding sum of first n primes are 2, 5, 10, 17, 41, 58, 100, 160, 197 and 281.
%e a(3) = 3 because 2 + 3 + 5 = 3^2 + 1^2.
%e a(5) = 6 because 2 + 3 + 5 + 7 + 11 + 13 = 5^2 + 4^2.
%e a(6) = 7 because 2 + 3 + 5 + 7 + 11 + 13 + 17 = 7^2 + 3^2.
%o (PARI) a(n) = sum(k=1, n, prime(k));
%o is(n) = { for( i=1, #n=factor(n)~%4, n[1, i]==3 && n[2, i]%2 && return); n && ( vecmin(n[1, ])==1 || (n[1, 1]==2 && n[2, 1]%2)) }
%o for(n=1, 1e3, if(is((a(n))), print1(n, ", ")))
%Y Cf. A000404, A007504.
%K nonn
%O 1,2
%A _Altug Alkan_, Nov 27 2015
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