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A037582
Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 1,3.
2
1, 13, 131, 1313, 13131, 131313, 1313131, 13131313, 131313131, 1313131313, 13131313131, 131313131313, 1313131313131, 13131313131313, 131313131313131, 1313131313131313, 13131313131313131, 131313131313131313, 1313131313131313131, 13131313131313131313
OFFSET
1,2
FORMULA
G.f.: x*(1+3*x) / ( (x-1)*(10*x-1)*(1+x) ). - R. J. Mathar, Aug 12 2013
MATHEMATICA
Table[FromDigits[PadRight[{}, n, {1, 3}]], {n, 20}] (* Harvey P. Dale, Feb 11 2015 *)
PROG
(PARI) Vec(x*(1+3*x)/((x-1)*(10*x-1)*(1+x)) + O(x^25)) \\ Jinyuan Wang, Apr 14 2020
CROSSREFS
Cf. A156641 (even bisection).
Sequence in context: A037708 A142740 A248919 * A065539 A048554 A293580
KEYWORD
nonn,base,easy
EXTENSIONS
More terms from Harvey P. Dale, Feb 11 2015
STATUS
approved