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

Author

Jon Perry, Nov 14 2012

Keywords

• nonn
• easy

Comments

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

Links

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

Crossrefs

Cf. A006516, A016142.

Programs

JavaScript

for (j=0;j<20;j++) document.write((Math.pow(3,j)-1)*Math.pow(3,j-1)+", ");

Mathematica

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

Maxima

A219205(n):=3^(n-1)*(3^n - 1)$ makelist(A219205(n),n,0,30); /* Martin Ettl, Nov 15 2012 */

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]

Extensions

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