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A131970
1 followed by 2n 2's.
1
1, 122, 12222, 1222222, 122222222, 12222222222, 1222222222222, 122222222222222, 12222222222222222, 1222222222222222222, 122222222222222222222, 12222222222222222222222
OFFSET
0,2
FORMULA
From Chai Wah Wu, Jun 17 2020: (Start)
a(n) = 101*a(n-1) - 100*a(n-2) for n > 1.
G.f.: (21*x + 1)/((x - 1)*(100*x - 1)). (End)
MATHEMATICA
NestList[FromDigits[PadRight[IntegerDigits[#], IntegerLength[#]+2, 2]]&, 1, 20] (* Harvey P. Dale, Mar 06 2011 *)
Table[FromDigits[PadRight[{1}, 2n+1, 2]], {n, 0, 20}] (* Harvey P. Dale, Jul 30 2020 *)
PROG
(Magma) [2*(10^(2*n)-1)/9+10^(2*n): n in [0..15]]; // Vincenzo Librandi, Aug 10 2011
CROSSREFS
Sequence in context: A275502 A275399 A275264 * A233096 A121916 A097843
KEYWORD
nonn,base,easy
AUTHOR
Paul Curtz, Oct 06 2007
STATUS
approved