A037589 Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 3,1.

3, 31, 313, 3131, 31313, 313131, 3131313, 31313131, 313131313, 3131313131, 31313131313, 313131313131, 3131313131313, 31313131313131, 313131313131313, 3131313131313131

Offset

1,1

Links

Table of n, a(n) for n=1..16.

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

Formula

G.f.: x*(3+x)/(1-10*x-x^2+10*x^3). - Jaume Oliver Lafont, Mar 24 2009

Mathematica

Table[FromDigits[PadRight[{}, n, {3, 1}]], {n, 20}] (* Harvey P. Dale, Oct 19 2016 *)

Crossrefs

Sequence in context: A113075 A111137 A037785 * A247351 A089289 A011545

Adjacent sequences: A037586 A037587 A037588 * A037590 A037591 A037592

Keyword

nonn,base,easy

Author

Clark Kimberling

Status

approved