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A050684 Number of nonzero palindromes < 10^n and containing at least one digit '1'. 2
1, 2, 20, 38, 290, 542, 3710, 6878, 44390, 81902, 509510, 937118, 5685590, 10434062, 62170310, 113906558, 669532790, 1225159022, 7125795110, 13026431198, 75132155990, 137237880782, 786189403910, 1435140927038 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (0,19,0,-90).

FORMULA

a(2n) = 2*(10^n - 9^n); a(2n + 1) = 2*(10^n - 9^n) + 9*10^n - 8*9^n. - David Wasserman, Feb 14 2002

EXAMPLE

Up to 10^2 we find two numbers 1 and 11.

MATHEMATICA

Table[If[EvenQ[n], 2*(10^(n/2) - 9^(n/2)) , 2*(10^((n - 1)/2) - 9^((n - 1)/2)) + 9*10^((n - 1)/2) - 8*9^((n - 1)/2)], {n, 25}] (* or *) LinearRecurrence[{0, 19, 0, -90}, {1, 2, 20, 38}, 25] (* G. C. Greubel, Oct 27 2016 *)

CROSSREFS

Cf. A050250, A050685.

Sequence in context: A293029 A298761 A062133 * A073214 A293356 A269669

Adjacent sequences:  A050681 A050682 A050683 * A050685 A050686 A050687

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Aug 15 1999.

EXTENSIONS

More terms from David Wasserman, Feb 14 2002

STATUS

approved

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Last modified March 20 21:49 EDT 2019. Contains 321352 sequences. (Running on oeis4.)