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%I #19 Apr 23 2024 08:28:30
%S 0,1,2,2,3,3,3,3,3,3,5,5,5,5,5,5,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
%T 7,7,8,8,8,8,10,10,10,10,10,10,10,10,10,10,10,10,12,12,12,12,12,12,14,
%U 14,14,14,14,14,14,14,14,14,14,14,14,14,15,15,15,15,15,15,15,15,15,15,17,17,17,17,17,17,17,17
%N a(n) = Sum_{primes p <= n} r_2(p-1)/4, where r_2(n) = A004018(n).
%H Amiram Eldar, <a href="/A331135/b331135.txt">Table of n, a(n) for n = 1..10000</a>
%H Yoichi Motohashi, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa16/aa1633.pdf">On the distribution of prime numbers which are of the form x^2+y^2+1</a>, Acta Arith. 16 (1969/70), 351-363. MR0288086 (44 #5284).
%t Accumulate[Table[If[PrimeQ[n], SquaresR[2, n-1], 0], {n, 1, 100}]/4] (* _Amiram Eldar_, Apr 23 2024 *)
%Y Cf. A004018, A331134.
%K nonn
%O 1,3
%A _N. J. A. Sloane_, Jan 11 2020