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A117861 Number of palindromes of length n (in base 9). 1
8, 8, 72, 72, 648, 648, 5832, 5832, 52488, 52488, 472392, 472392, 4251528, 4251528, 38263752, 38263752, 344373768, 344373768, 3099363912, 3099363912, 27894275208, 27894275208, 251048476872, 251048476872, 2259436291848, 2259436291848, 20334926626632 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (0,9).

FORMULA

a(n) = 8*9^floor((n-1)/2).

G.f.: 8*x*(1+x)/(1-9*x^2). a(n) = 8*3^(n-2)*(2-(-1)^n). - Bruno Berselli, Oct 24 2011

MATHEMATICA

Table[8 9^Floor[(n-1)/2], {n, 50}] (* Harvey P. Dale, Oct 21 2011 *)

CROSSREFS

Cf. A050683.

Cf. A055275.

Sequence in context: A019216 A020552 A272961 * A186984 A298962 A082798

Adjacent sequences:  A117858 A117859 A117860 * A117862 A117863 A117864

KEYWORD

nonn,base,easy

AUTHOR

Martin Renner, May 02 2006

EXTENSIONS

More terms from Harvey P. Dale, Oct 21 2011

STATUS

approved

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Last modified June 21 00:35 EDT 2021. Contains 345328 sequences. (Running on oeis4.)