A186948 a(n) = 3^n - 2*n.

1, 1, 5, 21, 73, 233, 717, 2173, 6545, 19665, 59029, 177125, 531417, 1594297, 4782941, 14348877, 43046689, 129140129, 387420453, 1162261429, 3486784361, 10460353161, 31381059565, 94143178781, 282429536433, 847288609393

Offset

0,3

Comments

Binomial transform is A186947. Binomial transform of A186948.

Links

Table of n, a(n) for n=0..25.

Index entries for linear recurrences with constant coefficients, signature (5,-7,3).

Formula

G.f.: (1 - 4x + 7x^2)/((1-x)^2*(1-3x)).

a(n) = 3*a(n-1) + 2*(2n-3). - Vincenzo Librandi, Mar 13 2011

a(n) = 5*a(n-1) - 7*a(n-2) + 3*a(n-3); a(0)=1, a(1)=1, a(2)=5. - Harvey P. Dale, Nov 24 2011

Mathematica

Table[3^n-2n, {n, 0, 30}] (* or *) LinearRecurrence[{5, -7, 3}, {1, 1, 5}, 30] (* Harvey P. Dale, Nov 24 2011 *)

Prog

(PARI) a(n)=3^n-2*n \\ Charles R Greathouse IV, Oct 16 2015

Crossrefs

Sequence in context: A055280 A268304 A273450 * A271251 A201435 A202507

Adjacent sequences: A186945 A186946 A186947 * A186949 A186950 A186951

Keyword

nonn,easy

Author

Paul Barry, Mar 01 2011

Status

approved