A166122 a(n) = (7-(-5)^n)/6.

1, 2, -3, 22, -103, 522, -2603, 13022, -65103, 325522, -1627603, 8138022, -40690103, 203450522, -1017252603, 5086263022, -25431315103, 127156575522, -635782877603, 3178914388022, -15894571940103, 79472859700522

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (-4,5).

Formula

a(n) = 5*a(n-2) - 4*a(n-1), a(0)= 1, a(1)= 2, for n>1.

a(n) = 7-5*a(n-1), a(0)=1.

a(n) = a(n-1)+(-5)^(n-1), a(0)=1.

O.g.f.: (1+6*x)/(1+4*x-5*x^2).

E.g.f.: (7*exp(x)-exp(-5*x))/6.

Mathematica

LinearRecurrence[{-4, 5}, {1, 2}, 30] (* Harvey P. Dale, Mar 10 2016 *)
Table[(7 - (-5)^n)/6, {n, 24}] (* or *)
CoefficientList[Series[(1 + 6 x)/(1 + 4 x - 5 x^2), {x, 0, 24}], x] (* Michael De Vlieger, Apr 27 2016 *)

Crossrefs

Cf. A084222, A084247, A166114.

Sequence in context: A268866 A154254 A264696 * A366405 A114996 A153256

Adjacent sequences: A166119 A166120 A166121 * A166123 A166124 A166125

Keyword

sign,easy

Author

Philippe Deléham, Oct 07 2009

Status

approved