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 A295996 One quarter of number of Gaussian primes whose norm is 4*n+1 or less. 5
 0, 3, 4, 6, 8, 8, 8, 10, 10, 12, 14, 14, 15, 17, 17, 19, 19, 19, 21, 21, 21, 21, 23, 23, 25, 27, 27, 29, 31, 31, 32, 32, 32, 32, 34, 34, 34, 36, 36, 38, 38, 38, 38, 40, 40, 42, 42, 42, 44, 46, 46, 46, 46, 46, 46, 46, 46, 48, 50, 50, 52, 52, 52, 52, 54, 54, 54, 56 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 Eric Weisstein's World of Mathematics, Gaussian Prime EXAMPLE The Gaussian primes whose norm is 9 or less;       *        3i,     *   *      -1+2i, 1+2i   * *   * *    -2+i, -1+i, 1+i, 2+i *           *  -3, 3   * *   * *    -2-i, -1-i, 1-i, 2-i     *   *      -1-2i, 1-2i       *        -3i                a(2) = 16/4 = 4. PROG (Ruby) require 'prime' def A(k, n)   ary = []   cnt = 0   k.step(4 * n + k, 4){|i|     cnt += 1 if i.prime?     ary << cnt   }   ary end def A295996(n)   ary1 = A(1, n)   ary3 = A(3, Math.sqrt(n).to_i) + [0]   [0] + (1..n).map{|i| 1 + 2 * ary1[i] + ary3[(Math.sqrt(4 * i + 1).to_i - 3) / 4]} end p A295996(100) CROSSREFS Cf. A016813, A055029, A091100, A091134, A135462, A296020, A296021. Sequence in context: A141219 A069211 A242822 * A240675 A072152 A199015 Adjacent sequences:  A295993 A295994 A295995 * A295997 A295998 A295999 KEYWORD nonn AUTHOR Seiichi Manyama, Dec 02 2017 STATUS approved

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Last modified September 28 10:51 EDT 2020. Contains 337393 sequences. (Running on oeis4.)