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A173770
a(n)=(4*10^n-13)/9.
3
3, 43, 443, 4443, 44443, 444443, 4444443, 44444443, 444444443, 4444444443, 44444444443, 444444444443, 4444444444443, 44444444444443, 444444444444443, 4444444444444443, 44444444444444443, 444444444444444443
OFFSET
1,1
FORMULA
a(n)=10*a(n-1)+13 (with a(1)=3).
G.f. x*(3+10*x) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Aug 23 2011
EXAMPLE
For n=2, a(2)=10*3+13=43; n=3, a(3)=10*43+13=443; n=4, a(4)=10*443+13=4443
CROSSREFS
Sequence in context: A138974 A036940 A099664 * A093163 A199020 A211959
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Feb 24 2010
STATUS
approved