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A037543
Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 1,2,1.
1
1, 12, 121, 1211, 12112, 121121, 1211211, 12112112, 121121121, 1211211211, 12112112112, 121121121121, 1211211211211, 12112112112112, 121121121121121, 1211211211211211
OFFSET
1,2
FORMULA
G.f.: x*(1+x)^2 / ( (x-1)*(10*x-1)*(1+x+x^2) ). - R. J. Mathar, Aug 12 2013
PROG
(PARI) Vec(x*(1+x)^2/((x-1)*(10*x-1)*(1+x+x^2)) + O(x^25)) \\ Jinyuan Wang, Apr 14 2020
CROSSREFS
Sequence in context: A018204 A176779 A098297 * A214317 A037487 A332603
KEYWORD
nonn,base,easy
STATUS
approved