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A198763
a(n) = 4*5^n-1.
1
3, 19, 99, 499, 2499, 12499, 62499, 312499, 1562499, 7812499, 39062499, 195312499, 976562499, 4882812499, 24414062499, 122070312499, 610351562499, 3051757812499, 15258789062499, 76293945312499, 381469726562499, 1907348632812499
OFFSET
0,1
FORMULA
a(n) = 5*a(n-1)+4.
a(n) = 6*a(n-1)-5*a(n-2), n>1.
G.f.: (3 + x)/(1 - 6*x + 5*x^2). - Vincenzo Librandi, Jan 04 2013
MATHEMATICA
CoefficientList[Series[(3 + x)/(1 - 6*x + 5*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 04 2013 *)
NestList[5#+4&, 3, 30] (* or *) LinearRecurrence[{6, -5}, {3, 19}, 30] (* Harvey P. Dale, Jul 03 2021 *)
PROG
(Magma) [4*5^n-1: n in [0..30]]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Oct 30 2011
STATUS
approved