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A095372 1+integers repeating "90" decimal digit pattern:. 6
1, 91, 9091, 909091, 90909091, 9090909091, 909090909091, 90909090909091, 9090909090909091, 909090909090909091, 90909090909090909091, 9090909090909090909091, 909090909090909090909091 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

These numbers arise for example as divisors of several repunits (A002275).

LINKS

Table of n, a(n) for n=0..12.

Index entries for linear recurrences with constant coefficients, signature (101,-100).

FORMULA

a(n) = 1+90*(-1+100^n)/99 = (10^(2n+1)+1)/11. - Rick L. Shepherd, Aug 01 2004

a(n) = (a(n-1)-1)*100+91, with a(0)=1. - Paolo P. Lava, Oct 21 2008

a(n) = 101*a(n-1)-100*a(n-2). G.f.: -(10*x-1) / ((x-1)*(100*x-1)). - Colin Barker, Jul 03 2013

EXAMPLE

Digit-pattern P=[ab..z] repeating integers equal formally with P*(-1+10^(Ln))/(-1+10^L), where L is the length of pattern;

a(9) divides A002275(38) repunit. See A095371.

MATHEMATICA

Table[1+90*(100^n-1)/99, {n, 0, 20}]

CROSSREFS

Cf. A002275, A095371.

Cf. A015585, A097209, A001562, A054416.

Sequence in context: A006244 A054216 A109627 * A165154 A015261 A168624

Adjacent sequences:  A095369 A095370 A095371 * A095373 A095374 A095375

KEYWORD

nonn,easy,base

AUTHOR

Labos Elemer, Jun 07 2004

STATUS

approved

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Last modified July 23 00:43 EDT 2019. Contains 325228 sequences. (Running on oeis4.)