A219205 a(n) = 3^(n-1)*(3^n - 1), n >= 0.

0, 2, 24, 234, 2160, 19602, 176904, 1593594, 14346720, 129133602, 1162241784, 10460294154, 94143001680, 847288078002, 7625595890664, 68630372581914, 617673381935040, 5559060523508802, 50031544969859544, 450283905503576874

Offset

0,2

Comments

Last digit has period 4: 0, 2, 4, 4.

Links

Table of n, a(n) for n=0..19.

Index entries for linear recurrences with constant coefficients, signature (12,-27).

Formula

a(n) = 2 * A016142(n-1).

a(n) = 12*a(n-1)-27*a(n-2). G.f.: 2*x/((3*x-1)*(9*x-1)). [Colin Barker, Nov 23 2012]

Mathematica

LinearRecurrence[{12, -27}, {0, 2}, 20] (* Hugo Pfoertner, Feb 14 2024 *)

Prog

(JavaScript)
for (j=0; j<20; j++) document.write((Math.pow(3, j)-1)*Math.pow(3, j-1)+", ");
(Maxima) A219205(n):=3^(n-1)*(3^n - 1)$ makelist(A219205(n), n, 0, 30); /* Martin Ettl, Nov 15 2012 */

Crossrefs

Cf. A006516, A016142.

Sequence in context: A180388 A288270 A221653 * A380582 A025131 A270564

Adjacent sequences: A219202 A219203 A219204 * A219206 A219207 A219208

Keyword

nonn,easy

Author

Jon Perry, Nov 14 2012

Extensions

a(19) corrected by Colin Barker, Nov 23 2012

Status

approved