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%I #13 Dec 09 2017 20:28:10
%S 0,1,1,2,3,3,3,4,4,5,6,6,6,7,7,8,8,8,9,9,9,9,10,10,11,12,12,13,14,14,
%T 14,14,14,14,15,15,15,16,16,17,17,17,17,18,18,19,19,19,20,21,21,21,21,
%U 21,21,21,21,22,23,23,24,24,24,24,25,25,25,26,26,27,28,28
%N Number of primes of the form 4*k+1 <= 4*n+1.
%H Seiichi Manyama, <a href="/A296021/b296021.txt">Table of n, a(n) for n = 0..10000</a>
%o (Ruby)
%o require 'prime'
%o def A(k, n)
%o ary = []
%o cnt = 0
%o k.step(4 * n + k, 4){|i|
%o cnt += 1 if i.prime?
%o ary << cnt
%o }
%o ary
%o end
%o p A(1, 100)
%Y Cf. A016813, A091098, A295996, A296020.
%K nonn
%O 0,4
%A _Seiichi Manyama_, Dec 02 2017
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