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A003098
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Palindromic triangular numbers.
(Formerly M2605)
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12
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1, 3, 6, 55, 66, 171, 595, 666, 3003, 5995, 8778, 15051, 66066, 617716, 828828, 1269621, 1680861, 3544453, 5073705, 5676765, 6295926, 35133153, 61477416, 178727871, 1264114621, 1634004361, 5289009825, 6172882716, 13953435931
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Charles W. Trigg, Palindromic Triangular Numbers, J. Rec. Math., 6 (1973), 146-147.
David Wells, The Penguin Dictionary of Curious and Interesting Numbers, p. 73 (Rev. ed. 1997)
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..147 (from P. De Geest)
P. De Geest, Palindromic Triangulars
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MATHEMATICA
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palQ[n_]:=Module[{idn=IntegerDigits[n]}, idn==Reverse[idn]]; Select[Accumulate[Range[200000]], palQ] (* From Harvey P. Dale, Mar 23 2011 *)
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CROSSREFS
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Cf. A008509, A002113, A000217.
Sequence in context: A032070 A066569 A051641 * A045914 A067610 A067609
Adjacent sequences: A003095 A003096 A003097 * A003099 A003100 A003101
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KEYWORD
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nonn,base,easy,nice
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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