A037582 Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 1,3.

1, 13, 131, 1313, 13131, 131313, 1313131, 13131313, 131313131, 1313131313, 13131313131, 131313131313, 1313131313131, 13131313131313, 131313131313131, 1313131313131313, 13131313131313131, 131313131313131313, 1313131313131313131, 13131313131313131313

Offset

1,2

Links

Table of n, a(n) for n=1..20.

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

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

Adjacent sequences: A037579 A037580 A037581 * A037583 A037584 A037585

Keyword

nonn,base,easy

Author

Clark Kimberling

Extensions

More terms from Harvey P. Dale, Feb 11 2015

Status

approved