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A037589 Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 3,1. 0
3, 31, 313, 3131, 31313, 313131, 3131313, 31313131, 313131313, 3131313131, 31313131313, 313131313131, 3131313131313, 31313131313131, 313131313131313, 3131313131313131 (list; graph; refs; listen; history; text; internal format)
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

a(n)=10*a(n-1)+2-(-1)^n, with a(0)=0. Closed form: a(n)=-(2/9)-(1/11)*(-1)^n+(31/99)*10^n, with n>=1. - Paolo P. Lava, Mar 31 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

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Last modified September 17 22:53 EDT 2019. Contains 327147 sequences. (Running on oeis4.)