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 A165135 The number of n-digit positive papaya numbers. 6
 9, 90, 252, 1872, 4464, 29250, 62946, 393912, 809442, 4945140, 9899910, 59366286, 116999892, 692936460, 1349989992, 7919601912, 15299999856, 89099130960, 170999999838, 989995038012, 1889999872488, 10889990099100, 20699999999802, 118799939782206, 224999999981964 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Papaya numbers are concatenations of two palindromes or palindromes themselves. All one-digit and two-digit numbers are papaya numbers. LINKS Andrew Howroyd, Table of n, a(n) for n = 1..200 Tanya Khovanova, Papaya Words and Numbers FORMULA a(n) = A052268(n)-A165611(n). - R. J. Mathar, Sep 25 2009 a(n) = 9*R(n,10)/10 - Sum_{d|n,dd, eulerphi(n/d)*a(d))); \\ Andrew Howroyd, Oct 14 2017 CROSSREFS Cf. A007055, A052268, A165610, A165611. Sequence in context: A140160 A043960 A044641 * A277105 A180289 A210088 Adjacent sequences:  A165132 A165133 A165134 * A165136 A165137 A165138 KEYWORD base,nonn AUTHOR Sergei Bernstein and Tanya Khovanova, Sep 04 2009 EXTENSIONS a(7)-a(8) from R. J. Mathar, Sep 25 2009 a(9)-a(25) from Andrew Howroyd, Mar 29 2016 STATUS approved

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Last modified December 13 08:08 EST 2018. Contains 318082 sequences. (Running on oeis4.)