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A066757
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Pentagonal numbers not divisible by 10 whose reverse is triangular.
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0
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0, 1, 12, 51, 18426, 69876, 6168162, 12105501, 17759001, 3008521945, 100938635992, 826471253301, 3044088035830227, 5889438558016867, 55959294872171901
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OFFSET
| 1,3
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EXAMPLE
| 51 is pentagonal and 15 is triangular
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MATHEMATICA
| dtn[L_] := Fold[10#1+#2&, 0, L] tritest[n_] := Module[{t}, t=Floor[N[Sqrt[2n]]]; 2n==t(t+1)] A={0}; For[i=1, i>0, i++, t=i(3i-1)/2; r=dtn[Reverse[IntegerDigits[t]]]; If[tritest[r]&&Mod[t, 10]>0, AppendTo[A, t]; Print[A]]]
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CROSSREFS
| Sequence in context: A166776 A200887 A115680 * A045219 A054410 A195544
Adjacent sequences: A066754 A066755 A066756 * A066758 A066759 A066760
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KEYWORD
| base,more,nonn
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AUTHOR
| Erich Friedman (efriedma(AT)stetson.edu), Jan 17 2002
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EXTENSIONS
| a(13)-a(15) from Lars Blomberg (lars.blomberg(AT)visit.se), May 18 2011
Description clarified and offset corrected by Lars Blomberg (lars.blomberg(AT)visit.se), May 29 2011
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