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%I #13 Aug 08 2022 09:15:17
%S 2,4,6,8,10,12,16,18,20,22,24,26,28,30,32,34,36,38,40,44,46,48,50,52,
%T 54,56,58,60,62,64,66,68,72,74,76,80,82,86,88,90,92,94,96,100,102,104,
%U 106,108,110,116,118,120,122,128,130,132,134,136,138,140,142,144,146,148
%N Even numbers k such that k^2 is in A014567.
%C Even numbers k such that k and sigma(k^2) are coprime, sigma = A000203.
%H Jianing Song, <a href="/A356448/b356448.txt">Table of n, a(n) for n = 1..7127</a> (all terms <= 20000)
%F a(n) = 2*A356451(n).
%e 12 is a term since 12 and sigma(12^2) = 403 are coprime.
%o (PARI) isA356448(n) = !(n%2) && gcd(n,sigma(n^2))==1
%Y Cf. A014567, A000203, A356382, A356449, A356451, A356452 (complement in the even numbers).
%K nonn,easy
%O 1,1
%A _Jianing Song_, Aug 07 2022
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