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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
OFFSET
1,1
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
KEYWORD
nonn,base,easy
AUTHOR
Martin Renner, May 02 2006
EXTENSIONS
More terms from Harvey P. Dale, Oct 21 2011
STATUS
approved