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A198962
5*9^n-1.
1
4, 44, 404, 3644, 32804, 295244, 2657204, 23914844, 215233604, 1937102444, 17433922004, 156905298044, 1412147682404, 12709329141644, 114383962274804, 1029455660473244, 9265100944259204, 83385908498332844, 750473176484995604
OFFSET
0,1
FORMULA
a(n) = 4*A138894(n).
a(n) = 9*a(n-1)+8, n>0.
a(n) = 10*a(n-1)-9*a(n-2), n>1.
G.f. ( 4+4*x ) / ( (9*x-1)*(x-1) ). - R. J. Mathar, Nov 01 2011
MATHEMATICA
5*9^Range[0, 30]-1 (* or *) LinearRecurrence[{10, -9}, {4, 44}, 30] (* Harvey P. Dale, Oct 20 2019 *)
PROG
(Magma) [5*9^n-1: n in [0..20]]
CROSSREFS
Sequence in context: A297384 A178294 A043039 * A002754 A187870 A216272
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 01 2011
STATUS
approved