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A094624 Expansion of x*(1+11*x+x^2)/((1-x)*(1+x)*(1-10*x^2)). 4
0, 1, 11, 12, 121, 122, 1221, 1222, 12221, 12222, 122221, 122222, 1222221, 1222222, 12222221, 12222222, 122222221, 122222222, 1222222221, 1222222222, 12222222221, 12222222222, 122222222221, 122222222222, 1222222222221, 1222222222222, 12222222222221 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Previous name: "Sequence whose n-th term digits sum to n."

n-th term digits are reversals of A094623(n).

LINKS

Colin Barker, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (0,11,0,-10).

FORMULA

a(n) = 10^(n/2)*(11/18 + 11*sqrt(10)/180 - (11*sqrt(10)/180 - 11/18)(-1)^n) - 13/18 - (-1)^n/2.

From Colin Barker, Dec 01 2015: (Start)

a(n) = 11*a(n-2) - 10*a(n-4) for n > 3.

G.f.: x*(1+11*x+x^2) / ((1-x)*(1+x)*(1-10*x^2)). (End)

PROG

(PARI) concat(0, Vec(x*(1+11*x+x^2)/((1-x)*(1+x)*(1-10*x^2)) + O(x^40))) \\ Colin Barker, Dec 01 2015

CROSSREFS

Cf. A094625, A094626.

Sequence in context: A110380 A164854 A033047 * A108218 A038326 A249312

Adjacent sequences:  A094621 A094622 A094623 * A094625 A094626 A094627

KEYWORD

nonn,base,easy

AUTHOR

Paul Barry, May 15 2004

STATUS

approved

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Last modified October 21 22:47 EDT 2019. Contains 328315 sequences. (Running on oeis4.)