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A033175 n 3's followed by 1. 11
1, 31, 331, 3331, 33331, 333331, 3333331, 33333331, 333333331, 3333333331, 33333333331, 333333333331, 3333333333331, 33333333333331, 333333333333331, 3333333333333331, 33333333333333331, 333333333333333331 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

F. Smarandache, Properties of numbers, University of Craiova, 1973.

LINKS

Muniru A Asiru, Table of n, a(n) for n = 0..990

Eric Weisstein's World of Mathematics, 3

Index entries for linear recurrences with constant coefficients, signature (11,-10)

FORMULA

a(n) = (10^(n+1) - 7)/3.

a(n) = 10*a(n-1) + 21 (with a(0)=1). - Vincenzo Librandi, Nov 17 2010

G.f.: ( 1+20*x ) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Aug 24 2011

MATHEMATICA

Table[FromDigits[PadLeft[{1}, n, 3]], {n, 20}] (* Harvey P. Dale, Feb 21 2013 *)

PROG

(PARI) a(n)=(10^(n+1)-7)/3 \\ Charles R Greathouse IV, Oct 07 2015

(GAP) List([0..20], n->(10^(n+1)-7)/3); # Muniru A Asiru, Oct 31 2018

CROSSREFS

Cf. A051200.

Sequence in context: A029813 A138697 A186071 * A123568 A111675 A142495

Adjacent sequences:  A033172 A033173 A033174 * A033176 A033177 A033178

KEYWORD

nonn,base,easy

AUTHOR

Jan Jensen (dorul(AT)post6.tele.dk)

STATUS

approved

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Last modified February 22 19:54 EST 2019. Contains 320403 sequences. (Running on oeis4.)