A237990 Numbers m such that the numbers of primes, even positive integers and odd positive integers less than or equal to m are all even.

4, 8, 16, 20, 40, 44, 56, 64, 72, 80, 92, 96, 108, 116, 120, 124, 132, 136, 140, 144, 148, 152, 156, 164, 176, 184, 188, 196, 200, 204, 208, 224, 232, 240, 252, 256, 264, 268, 272

Offset

1,1

Comments

A subsequence of A008586.

Links

Ivan N. Ianakiev, Table of n, a(n) for n = 1..10000

Formula

a(n) == 0 (mod 4)

Example

A tetrahedral die whose faces are marked with the numbers from 1 to 4 has an even number of sides marked with prime numbers, even integers and odd integers. Therefore, 4 is in the sequence.

Mathematica

Select[Range[4, 1000, 4], EvenQ[PrimePi[#]] &] (* Paolo Xausa, Jun 24 2024 *)

Crossrefs

Cf. A008586, A237989.

Sequence in context: A181471 A272753 A272804 * A335792 A312807 A312808

Adjacent sequences: A237987 A237988 A237989 * A237991 A237992 A237993

Keyword

nonn,easy

Author

Ivan N. Ianakiev, Feb 16 2014

Status

approved