A026809 a(n) = 3^n*(3^n-1)*(3^n-2)/6.

0, 1, 84, 2925, 85320, 2362041, 64304604, 1741001445, 47050068240, 1270739210481, 34313445309924, 926494403955165, 25015631334908760, 675424587904113321, 18236486750190760044, 492385348146244352085, 13294406252968671566880

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 0..690
• Index entries for linear recurrences with constant coefficients, signature (39, -351, 729).

Crossrefs

Subsequence of A000292.

Programs

GAP

List([0..20], n-> Binomial(3^n, 3) ); # G. C. Greubel, Nov 08 2019

Magma

[Binomial(3^n, 3): n in [0..20]]; // G. C. Greubel, Nov 08 2019

Maple

seq(binomial(3^n,3),n=0..16); # Zerinvary Lajos, Jan 07 2008

Mathematica

Binomial[3^Range[0, 20], 3] (* G. C. Greubel, Nov 08 2019 *)

PARI

vector(21, n, binomial(3^(n-1), 3) ) \\ G. C. Greubel, Nov 08 2019

Sage

[binomial(3^n, 3) for n in (0..20)] # G. C. Greubel, Nov 08 2019

Formula

a(n) = binomial(3^n, 3), n >= 0. - Zerinvary Lajos, Jan 07 2008