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 A066741 Pentagonal numbers not divisible by 10 whose reverse is a square. 0
 0, 1, 925, 1426, 6112, 9801, 140301, 52244922262, 1445531162626, 5205252778462, 63253297234426, 9040940929621480310251 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(13) > 2^63. - Donovan Johnson, May 24 2011 LINKS Table of n, a(n) for n=1..12. EXAMPLE 925 is pentagonal and 529 is square 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]]] CROSSREFS Cf. A000326. Sequence in context: A172702 A159701 A115696 * A325141 A244169 A245791 Adjacent sequences: A066738 A066739 A066740 * A066742 A066743 A066744 KEYWORD base,more,nonn AUTHOR Erich Friedman, Jan 16 2002 EXTENSIONS a(12) from Donovan Johnson, Apr 03 2008 Offset corrected by Donovan Johnson, May 24 2011 Description clarified and a(12) corrected by Lars Blomberg, May 29 2011 STATUS approved

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Last modified August 8 16:21 EDT 2024. Contains 375023 sequences. (Running on oeis4.)