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A173772 (4*10^n + 23)/9. 4
7, 47, 447, 4447, 44447, 444447, 4444447, 44444447, 444444447, 4444444447, 44444444447, 444444444447, 4444444444447, 44444444444447, 444444444444447, 4444444444444447, 44444444444444447, 444444444444444447 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = 10*a(n-1)-23 with n>1, a(1)=7.
a(n) = 11*a(n-1)-10*a(n-2). G.f.: -x*(30*x-7)/((x-1)*(10*x-1)). [Colin Barker, Jan 24 2013]
MATHEMATICA
LinearRecurrence[{11, -10}, {7, 47}, 30] (* or *) Table[FromDigits[ PadLeft[ {7}, n, 4]], {n, 30}] (* Harvey P. Dale, Dec 27 2014 *)
PROG
(PARI) a(n)=4*10^n\9+3 \\ Charles R Greathouse IV, Jan 11 2012
CROSSREFS
Sequence in context: A093173 A368177 A218761 * A178002 A288722 A006873
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 24 2010
STATUS
approved

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Last modified March 28 10:55 EDT 2024. Contains 371241 sequences. (Running on oeis4.)