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A050720 Number of nonzero palindromes of length n containing the digit '0'. 3
0, 0, 9, 9, 171, 171, 2439, 2439, 30951, 30951, 368559, 368559, 4217031, 4217031, 46953279, 46953279, 512579511, 512579511, 5513215599, 5513215599, 58618940391, 58618940391, 617570463519, 617570463519, 6458134171671 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
FORMULA
G.f.: 9*x^3*(x+1) / ((3*x-1)*(3*x+1)*(10*x^2-1)). - Colin Barker, Feb 15 2013
For n > 1, a(n) = 9*10^(k-1) - 9^k, where k = ceiling(n/2). - Jon E. Schoenfield, Sep 14 2013
EXAMPLE
For length 3 we find nine numbers: 101, 202, ... 909, so a(3) = 9.
MATHEMATICA
nzp[n_]:=Module[{k=Ceiling[n/2]}, 9*10^(k-1)-9^k]; Array[nzp, 30] (* Harvey P. Dale, Jun 01 2019 *)
CROSSREFS
Sequence in context: A092548 A121389 A065242 * A262860 A335026 A353182
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Aug 15 1999
EXTENSIONS
More terms from Michael Lugo (mlugo(AT)thelabelguy.com), Dec 22 1999
Corrected by T. D. Noe, Nov 08 2006
STATUS
approved

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Last modified June 15 09:26 EDT 2024. Contains 373407 sequences. (Running on oeis4.)