

A016190


Expansion of 1/((19x)(111x)).


4



1, 20, 301, 4040, 51001, 620060, 7352101, 85656080, 985263601, 11225320100, 126965305501, 1427999420120, 15990423157801, 178436520564140, 1985678518660501, 22048354837360160, 244384923399813601
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OFFSET

0,2


COMMENTS

a(n1), n >= 0, with a(1) = 0, is also the number of words of length n, over an alphabet of eleven letters, of which any chosen one appears an odd number of times. See the Jul 22 2003 comment in A006516 (4letter case) and the Balakrishnan reference there.  Wolfdieter Lang, Jul 18 2017


LINKS

Table of n, a(n) for n=0..16.
Index entries for linear recurrences with constant coefficients, signature (20,99).


FORMULA

a(n) = (11^(n+1)9^(n+1))/2.  Bruno Berselli, Feb 09 2011
From Vincenzo Librandi, Feb 09 2011: (Start)
a(n) = 11*a(n1)+9^n, a(0)=1.
a(n) = 20*a(n1)99*a(n2), a(0)=1, a(1)=20. (End)


MATHEMATICA

CoefficientList[Series[1/((19x)(111x)), {x, 0, 20}], x] (* or *) LinearRecurrence[{20, 99}, {1, 20}, 20] (* Harvey P. Dale, Jun 27 2017 *)


PROG

(PARI) Vec(1/((19*x)*(111*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012


CROSSREFS

Cf. A006516, A081203.
Sequence in context: A053541 A004345 A001755 * A016188 A006300 A282372
Adjacent sequences: A016187 A016188 A016189 * A016191 A016192 A016193


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane


STATUS

approved



