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A328332 Expansion of (1 + 4*x - 5*x^2 + 10*x^3) / ((1 - x) * (1 - 10*x^2)). 2
1, 5, 10, 60, 110, 610, 1110, 6110, 11110, 61110, 111110, 611110, 1111110, 6111110, 11111110, 61111110, 111111110, 611111110, 1111111110, 6111111110, 11111111110, 61111111110, 111111111110, 611111111110, 1111111111110, 6111111111110, 11111111111110, 61111111111110, 111111111111110 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Number of odd palindromes <= 10^n.

LINKS

Table of n, a(n) for n=0..28.

Eric Weisstein's World of Mathematics, Palindromic Number

Index entries for linear recurrences with constant coefficients, signature (1,10,-10).

MATHEMATICA

nmax = 28; CoefficientList[Series[(1 + 4 x - 5 x^2 + 10 x^3) / ((1 - x) (1 - 10 x^2)), {x, 0, nmax}], x]

Join[{1}, LinearRecurrence[{1, 10, -10}, {5, 10, 60}, 28]]

PROG

(PARI) Vec((1 + 4*x - 5*x^2 + 10*x^3) / ((1 - x) * (1 - 10*x^2)) + O(x^30)) \\ Michel Marcus, Oct 13 2019

CROSSREFS

Cf. A002113, A029950, A050250, A070199, A328333.

Sequence in context: A271295 A005438 A072309 * A240647 A061518 A062162

Adjacent sequences:  A328329 A328330 A328331 * A328333 A328334 A328335

KEYWORD

nonn,base,easy

AUTHOR

Ilya Gutkovskiy, Oct 12 2019

STATUS

approved

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Last modified August 8 02:45 EDT 2020. Contains 336290 sequences. (Running on oeis4.)