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%I #16 Aug 13 2024 05:31:14
%S 195938,224450,13645088,15870978,18180450,29184800,1105252128,
%T 2363968800,2686005218,2917410498,3564550178,5056357922,8442721568,
%U 10814792450,18587462432,21292224800,48666384162,140836104992,212352534818,217566422658,288728564418,315325993248
%N Numbers of the form 2*k^2 such that sigma(2*k^2) is an odd square.
%C No terms whose sum of divisors is a square of a prime below 10^12 were found.
%H Amiram Eldar, <a href="/A074388/b074388.txt">Table of n, a(n) for n = 1..200</a> (calculated using the b-file at A097023)
%F a(n) = 2*A097023(n)^2. - _Amiram Eldar_, Aug 13 2024
%e 195938 = 2*313^2 and sigma(195938) = 294849 = 543^2.
%t Do[s=DivisorSigma[1, 2*(n^2)]; If[IntegerQ[Sqrt[s]]&&Mod[s, 2]==1, Print[2*(n^2)]], {n, 1, 10000000}]
%Y Cf. A000203, A001248, A028982, A074386, A097023.
%K nonn
%O 1,1
%A _Labos Elemer_, Aug 22 2002
%E a(19)-a(22) from _Amiram Eldar_, Aug 13 2024