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A199308
(7*5^n+1)/4.
1
2, 9, 44, 219, 1094, 5469, 27344, 136719, 683594, 3417969, 17089844, 85449219, 427246094, 2136230469, 10681152344, 53405761719, 267028808594, 1335144042969, 6675720214844, 33378601074219, 166893005371094, 834465026855469
OFFSET
0,1
FORMULA
a(n) = 5*a(n-1)-1.
a(n) = 6*a(n-1)-5*a(n-2).
G.f.: (2-3*x)/((1-x)*(1-5*x)).
PROG
(Magma) [(7*5^n+1)/4: n in [0..30]];
CROSSREFS
Sequence in context: A365038 A013981 A216861 * A176479 A162356 A364476
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 05 2011
STATUS
approved