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A172174
a(n) = 90*a(n-1) + 1.
1
1, 91, 8191, 737191, 66347191, 5971247191, 537412247191, 48367102247191, 4353039202247191, 391773528202247191, 35259617538202247191, 3173365578438202247191, 285602902059438202247191, 25704261185349438202247191, 2313383506681449438202247191
OFFSET
1,2
COMMENTS
Difference of pairs of integers given in A162849.
Sum of digits give A017173.
FORMULA
From Colin Barker, Oct 02 2015: (Start)
a(n) = 91*a(n-1) - 90*a(n-2) for n>2.
G.f.: 1 / ((1-x)*(1-90*x)). (End)
MATHEMATICA
NestList[90#+1&, 1, 20] (* Harvey P. Dale, Aug 29 2014 *)
PROG
(PARI) Vec(1/((x-1)*(90*x-1)) + O(x^30)) \\ Colin Barker, Oct 02 2015
(SageMath) [(90^n -1)/89 for n in (1..50)] # G. C. Greubel, Apr 26 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mark Dols, Jan 28 2010
STATUS
approved