A356452 Even numbers k such that k^2 is not in A014567; complement of A356448 in the even numbers.

14, 42, 70, 78, 84, 98, 112, 114, 124, 126, 154, 156, 168, 182, 186, 198, 210, 222, 228, 234, 238, 252, 258, 266, 294, 308, 310, 312, 322, 336, 342, 350, 366, 372, 378, 390, 396, 402, 406, 418, 420, 434, 438, 444, 456, 462, 468, 474, 490, 504, 516, 518, 532, 546, 550, 558

Offset: 1

Author

Jianing Song, Aug 07 2022

Keywords

• nonn
• easy

Comments

Even numbers k such that k and sigma(k^2) are not coprime, sigma = A000203.

Examples

			14 is a term since 14 and sigma(14^2) = 399 have a common factor 7.
		

Links

• Jianing Song, Table of n, a(n) for n = 1..12241 (all terms <= 80000)

Crossrefs

Cf. A014567, A000203, A356448, A356453, A356454.

Programs

Mathematica

Select[2 Range[300],!CoprimeQ[#,DivisorSigma[1,#^2]]&] (* Harvey P. Dale, Mar 09 2023 *)

PARI

isA356452(n) = !(n%2) && gcd(n, sigma(n^2))>1

Formula

a(n) = 2*A356454(n).