A198766 a(n) = (7*5^n - 1)/2.

3, 17, 87, 437, 2187, 10937, 54687, 273437, 1367187, 6835937, 34179687, 170898437, 854492187, 4272460937, 21362304687, 106811523437, 534057617187, 2670288085937, 13351440429687, 66757202148437, 333786010742187, 1668930053710937

Offset

0,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (6,-5).

Formula

a(n) = 5*a(n-1)+2.

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

E.g.f.: exp(x)*(7*exp(4*x) - 1)/2. - Stefano Spezia, Mar 08 2025

Mathematica

CoefficientList[Series[(3 - x)/(1 - 6*x + 5*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jan 04 2013 *)
LinearRecurrence[{6, -5}, {3, 17}, 30] (* Harvey P. Dale, Jan 23 2015 *)

Prog

(Magma) [(7*5^n-1)/2: n in [0..30]];

Crossrefs

Cf. A024049, A057651, A081655.

Sequence in context: A143549 A037794 A203851 * A240652 A204092 A221731

Adjacent sequences: A198763 A198764 A198765 * A198767 A198768 A198769

Keyword

nonn,easy,changed

Author

Vincenzo Librandi, Oct 30 2011

Status

approved