A328332 - OEIS

A328332

Expansion of (1 + 4*x - 5*x^2 + 10*x^3) / ((1 - x) * (1 - 10*x^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

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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).

FORMULA

G.f.: (1 + 4*x - 5*x^2 + 10*x^3) / ((1 - x) * (1 - 10*x^2)).

a(n) = a(n-1) + 10*a(n-2) - 10*a(n-3). - Wesley Ivan Hurt, Aug 25 2022