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A066741
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Pentagonal numbers not divisible by 10 whose reverse is a square.
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0
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0, 1, 925, 1426, 6112, 9801, 140301, 52244922262, 1445531162626, 5205252778462, 63253297234426, 9040940929621480310251
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| a(13) > 2^63. - Donovan Johnson, May 24 2011
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EXAMPLE
| 925 is pentagonal and 529 is square
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MATHEMATICA
| dtn[L_] := Fold[10#1+#2&, 0, L] A={0}; For[i=1, i>0, i++, t=i(3i-1)/2; r=dtn[Reverse[IntegerDigits[t]]]; If[IntegerQ[Sqrt[r]]&&Mod[t, 10]>0, AppendTo[A, t]; Print[A]]]
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CROSSREFS
| Sequence in context: A172702 A159701 A115696 * A147548 A116989 A152503
Adjacent sequences: A066738 A066739 A066740 * A066742 A066743 A066744
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KEYWORD
| base,more,nonn
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AUTHOR
| Erich Friedman (efriedma(AT)stetson.edu), Jan 16 2002
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EXTENSIONS
| a(12) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Apr 03 2008
Offset corrected by Donovan Johnson (donovan.johnson(AT)yahoo.com), May 24 2011
Description clarified and a(12) corrected by Lars Blomberg (lars.blomberg(AT)visit.se), May 29 2011
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