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Search: id:A109859
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| 1, 2, 2, 6, 6, 20, 20, 70, 70, 251, 251, 918, 917, 3404, 3396, 12750, 12705, 48125, 47905, 182735, 181743, 697193, 692924, 2670538, 2652676, 10263255, 10189830, 39554920, 39256570, 152819066, 151616215, 591672286, 586848959, 2295096732
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Can some one find a formula for the n-th term?
At first a(2n) = a(2n+1) because the palindromes of sum 2n can be placed into one-to-one correpsondence with the palindromes of sum 2n+1 by inserting a 1 in the middle (if the number of digits is even) or adding one to the middle digit (if the number of digits is odd). However once there exists a palindrome with middle digit 9, this strategy no longer works. - Joshua Zucker (joshua.zucker(AT)stanfordalumni.org), May 05 2006
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CROSSREFS
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Cf. A109858.
Sequence in context: A117855 A086442 A071407 this_sequence A128057 A128014 A135401
Adjacent sequences: A109856 A109857 A109858 this_sequence A109860 A109861 A109862
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KEYWORD
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base,hard,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jul 08 2005
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EXTENSIONS
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More terms from Joshua Zucker (joshua.zucker(AT)stanfordalumni.org), May 05 2006
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