login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A219205 3^(n-1)*(3^n - 1), n >= 0. 1
0, 2, 24, 234, 2160, 19602, 176904, 1593594, 14346720, 129133602, 1162241784, 10460294154, 94143001680, 847288078002, 7625595890664, 68630372581914, 617673381935040, 5559060523508802, 50031544969859544, 450283905503576874 (list; graph; refs; listen; history; text; internal format)
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]

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 * A025131 A270564 A143407

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 15 06:11 EST 2019. Contains 329144 sequences. (Running on oeis4.)