A057811 Numbers k such that pi(k) is even.

1, 3, 4, 7, 8, 9, 10, 13, 14, 15, 16, 19, 20, 21, 22, 29, 30, 37, 38, 39, 40, 43, 44, 45, 46, 53, 54, 55, 56, 57, 58, 61, 62, 63, 64, 65, 66, 71, 72, 79, 80, 81, 82, 89, 90, 91, 92, 93, 94, 95, 96, 101, 102, 107, 108, 113, 114, 115, 116, 117, 118, 119

Offset

1,2

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Ping Ngai Chung and Shiyu Li, On the residue classes of π(n) modulo t, INTEGERS: Electronic Journal of Combinatorial Number Theory 13 (2013), A79.

Formula

Chang & Li show that a(n) < 64n + o(1), and a(n) < 8n + o(1) under the Hardy-Littlewood prime tuples conjecture. - Charles R Greathouse IV, Dec 19 2014

Mathematica

Select[Range[120], EvenQ[PrimePi[#]]&] (* Harvey P. Dale, Apr 10 2024 *)

Prog

(PARI) is(n)=primepi(n)%2==0 \\ Charles R Greathouse IV, Dec 19 2014

Crossrefs

Cf. A000720, A057812.

Sequence in context: A232779 A086986 A346126 * A284489 A026343 A080722

Adjacent sequences: A057808 A057809 A057810 * A057812 A057813 A057814

Keyword

nonn

Author

N. J. A. Sloane, Nov 07 2000

Status

approved