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Search: id:A066569
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| A066569 |
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Triangular numbers whose reverse is also triangular. |
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+0
1
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| 1, 3, 6, 55, 66, 153, 171, 351, 595, 666, 3003, 5995, 8778, 15051, 17578, 66066, 87571, 185745, 547581, 617716, 828828, 1269621, 1461195, 1680861, 3544453, 5073705, 5676765, 5911641, 6295926, 12145056, 12517506, 35133153, 60571521
(list; graph; listen)
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OFFSET
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0,2
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EXAMPLE
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153 and 351 are both 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={}; For[i=1, i>0, i++, t=i(i+1)/2; If[tritest[dtn[Reverse[IntegerDigits[t]]]]&&Mod[t, 10]>0, AppendTo[A, t]; Print[A]]]
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CROSSREFS
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Sequence in context: A023177 A132474 A032070 this_sequence A051641 A003098 A045914
Adjacent sequences: A066566 A066567 A066568 this_sequence A066570 A066571 A066572
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KEYWORD
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base,nonn
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AUTHOR
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Erich Friedman (efriedma(AT)stetson.edu), Jan 08 2002
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