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A037519
Decimal expansion of a(n) is given by the first n terms of the periodic sequence with initial period 2,0,1.
1
2, 20, 201, 2012, 20120, 201201, 2012012, 20120120, 201201201, 2012012012, 20120120120, 201201201201, 2012012012012, 20120120120120, 201201201201201, 2012012012012012
OFFSET
1,1
FORMULA
G.f.: (x*(2+x^2)) / ((x-1)*(10*x-1)*(1+x+x^2)). - R. J. Mathar, Nov 21 2011
MATHEMATICA
LinearRecurrence[{10, 0, 1, -10}, {2, 20, 201, 2012}, 40] (* Vincenzo Librandi, Nov 23 2011 *)
Table[FromDigits[PadRight[{}, n, {2, 0, 1}]], {n, 20}] (* Harvey P. Dale, Sep 18 2018 *)
PROG
(Magma) I:=[2, 20, 201, 2012]; [n le 4 select I[n] else 10*Self(n-1)+Self(n-3)-10*Self(n-4): n in [1..20]]; // Vincenzo Librandi, Nov 23 2011
CROSSREFS
Sequence in context: A136902 A136884 A093136 * A037722 A109107 A037729
KEYWORD
nonn,base,easy
STATUS
approved