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 A028985 Nonsquare palindromes whose sum of divisors is odd. 1
 2, 8, 242, 20402, 24642, 2004002, 2138312, 2468642, 85099058, 200040002, 204060402, 242484242, 291080192, 20000400002, 20442824402, 24204840242, 29956665992, 88484148488, 297738837792, 2000004000002, 2004006004002, 2040608060402, 2420048400242 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Palindromes of the form 2*k^2, with k a nonzero integer. - Stéphane Rézel, Jan 04 2018 LINKS Stéphane Rézel, Table of n, a(n) for n = 1..68 MATHEMATICA Select[Array[2 #^2 &, 10^7], PalindromeQ] (* Michael De Vlieger, Jan 10 2018 *) PROG (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 CROSSREFS Sequence in context: A009588 A338543 A125264 * A067583 A120378 A012345 Adjacent sequences:  A028982 A028983 A028984 * A028986 A028987 A028988 KEYWORD nonn,base AUTHOR EXTENSIONS Offset corrected and a(14)-a(21) from Donovan Johnson, Apr 25 2010 a(22)-a(23) from Donovan Johnson, Jun 16 2011 STATUS approved

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Last modified August 6 00:36 EDT 2021. Contains 346493 sequences. (Running on oeis4.)