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A028985
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Nonsquare palindromes whose sum of divisors is odd.
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0
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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; internal format)
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OFFSET
| 1,1
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MATHEMATICA
| r[n_]:=FromDigits[Reverse[IntegerDigits[n, 10]], 10]; f[n_]:=n==r[n]&&IntegerQ[Sqrt[n+r[n]]]; Timing[lst={}; Do[If[f[n], AppendTo[lst, n]], {n, 1, 12!}]; lst] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 10 2009]
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CROSSREFS
| Sequence in context: A091503 A009588 A125264 * A067583 A120378 A012345
Adjacent sequences: A028982 A028983 A028984 * A028986 A028987 A028988
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KEYWORD
| nonn,base
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com)
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EXTENSIONS
| Offset corrected and a(14)-a(21) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Apr 25 2010
a(22)-a(23) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Jun 16 2011
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