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Search: id:A066758
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| A066758 |
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Triangular numbers whose reverse is pentagonal. |
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+0
1
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| 0, 1, 15, 21, 62481, 67896, 2618616, 10095771, 10550121, 5491258003, 103352174628, 299536839001
(list; graph; listen)
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OFFSET
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0,3
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EXAMPLE
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51 is pentagonal and 15 is triangular
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MATHEMATICA
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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, r]; Print[A]]]
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CROSSREFS
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Sequence in context: A083372 A119101 A084931 this_sequence A018888 A115174 A092783
Adjacent sequences: A066755 A066756 A066757 this_sequence A066759 A066760 A066761
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KEYWORD
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base,more,nonn
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AUTHOR
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Erich Friedman (efriedma(AT)stetson.edu), Jan 17 2002
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