A356448 Even numbers k such that k^2 is in A014567.

2, 4, 6, 8, 10, 12, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 72, 74, 76, 80, 82, 86, 88, 90, 92, 94, 96, 100, 102, 104, 106, 108, 110, 116, 118, 120, 122, 128, 130, 132, 134, 136, 138, 140, 142, 144, 146, 148

Offset

1,1

Comments

Even numbers k such that k and sigma(k^2) are coprime, sigma = A000203.

Links

Jianing Song, Table of n, a(n) for n = 1..7127 (all terms <= 20000)

Formula

a(n) = 2*A356451(n).

Example

12 is a term since 12 and sigma(12^2) = 403 are coprime.

Prog

(PARI) isA356448(n) = !(n%2) && gcd(n, sigma(n^2))==1

Crossrefs

Cf. A014567, A000203, A356382, A356449, A356451, A356452 (complement in the even numbers).

Sequence in context: A011860 A259278 A049445 * A340521 A002174 A002202

Adjacent sequences: A356445 A356446 A356447 * A356449 A356450 A356451

Keyword

nonn,easy

Author

Jianing Song, Aug 07 2022

Status

approved