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A120309 Numbers k such that pi(k) == 0 (mod 4), where pi() = A000720. 2
1, 7, 8, 9, 10, 19, 20, 21, 22, 37, 38, 39, 40, 53, 54, 55, 56, 57, 58, 71, 72, 89, 90, 91, 92, 93, 94, 95, 96, 107, 108, 131, 132, 133, 134, 135, 136, 151, 152, 153, 154, 155, 156, 173, 174, 175, 176, 177, 178, 193, 194, 195, 196 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MATHEMATICA
a = Flatten[Table[If[Mod[PrimePi[n], 4] == 0, n, {}], {n, 1, 200}]]
PROG
(PARI) isok(k) = (primepi(k) % 4) == 0; \\ Michel Marcus, Feb 09 2021
CROSSREFS
Cf. A000720.
Sequence in context: A356635 A343297 A106108 * A035705 A205698 A210147
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Jun 20 2006
EXTENSIONS
Edited by N. J. A. Sloane, Jul 22 2006
STATUS
approved

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Last modified April 18 16:22 EDT 2024. Contains 371780 sequences. (Running on oeis4.)