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A050686
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Number of palindromes of length n and containing the digit 1 (or any other fixed nonzero digit).
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1
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1, 1, 18, 18, 252, 252, 3168, 3168, 37512, 37512, 427608, 427608, 4748472, 4748472, 51736248, 51736248, 555626232, 555626232, 5900636088, 5900636088, 62105724792, 62105724792, 648951523128, 648951523128, 6740563708152
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,3
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LINKS
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Table of n, a(n) for n=1..25.
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FORMULA
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Empirical g.f.: -x*(x-1)*(x+1)^2 / ((3*x-1)*(3*x+1)*(10*x^2-1)). [Colin Barker, Feb 15 2013]
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EXAMPLE
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For length 3 we find 18 numbers: 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 212, 313, 414, 515, 616, 717, 818, 919.
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CROSSREFS
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Cf. A050683, A050720.
Sequence in context: A040307 A022352 A211411 * A165839 A177014 A004459
Adjacent sequences: A050683 A050684 A050685 * A050687 A050688 A050689
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KEYWORD
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nonn,base
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AUTHOR
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Patrick De Geest, Aug 15 1999.
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EXTENSIONS
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More terms from Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999
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STATUS
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approved
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