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%I #43 Feb 21 2023 02:07:59
%S 2,8,242,20402,24642,2004002,2138312,2468642,85099058,200040002,
%T 204060402,242484242,291080192,20000400002,20442824402,24204840242,
%U 29956665992,88484148488,297738837792,2000004000002,2004006004002,2040608060402,2420048400242
%N Nonsquare palindromes whose sum of divisors is odd.
%C Palindromes of the form 2*k^2, with k a nonzero integer. - _Stéphane Rézel_, Jan 04 2018
%H Stéphane Rézel, <a href="/A028985/b028985.txt">Table of n, a(n) for n = 1..68</a>
%H Proof Wiki, <a href="https://proofwiki.org/wiki/Sigma_Function_Odd_iff_Argument_is_Square_or_Twice_Square">Sigma_Function_Odd_iff_Argument_is_Square_or_Twice_Square</a>
%t Select[Array[2 #^2 &, 10^7], PalindromeQ] (* _Michael De Vlieger_, Jan 10 2018 *)
%o (PARI) for(n=1,10^9,my(d=digits(2*n^2));if(d==Vecrev(d),print1(2*n^2,", "))); \\ _Joerg Arndt_, Jan 10 2018
%K nonn,base
%O 1,1
%A _Patrick De Geest_
%E Offset corrected and a(14)-a(21) from _Donovan Johnson_, Apr 25 2010
%E a(22)-a(23) from _Donovan Johnson_, Jun 16 2011
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