A356451 Numbers k such that 4*k^2 is in A014567.

1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 36, 37, 38, 40, 41, 43, 44, 45, 46, 47, 48, 50, 51, 52, 53, 54, 55, 58, 59, 60, 61, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 79, 80, 81, 82, 83

Offset: 1

Author

Jianing Song, Aug 07 2022

Keywords

• nonn
• easy

Comments

Numbers k such that k and sigma(4*k^2) are coprime, sigma = A000203.

Examples

			12 is a term since 12 and sigma(4*12^2) = 1651 are coprime.
		

Links

• Jianing Song, Table of n, a(n) for n = 1..7127 (all terms <= 10000)

Crossrefs

Cf. A014567, A000203, A356382, A356448, A356449, A356454 (complement).

Programs

PARI

isA356450(n) = gcd(n,sigma(4*n^2))==1

Formula

a(n) = A356448(n)/2.