A117861 Number of palindromes of length n (in base 9).

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

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