A169604 a(n) = 3*6^n.

3, 18, 108, 648, 3888, 23328, 139968, 839808, 5038848, 30233088, 181398528, 1088391168, 6530347008, 39182082048, 235092492288, 1410554953728, 8463329722368, 50779978334208, 304679870005248, 1828079220031488, 10968475320188928, 65810851921133568, 394865111526801408

Offset: 0

Author

Klaus Brockhaus, Apr 04 2010

Keywords

• nonn
• easy

Comments

a(n) = A081341(n+1).

Essentially first differences of A125682.

Binomial transform of A005053 without initial term 1.

Second binomial transform of A164346.

Inverse binomial transform of A169634.

Second inverse binomial transform of A103333 without initial term 1.

Contribution from Reinhard Zumkeller, May 02 2010: (Start)

a(n) = 3*A000400(n) = A000400(n+1)/2;

subsequence of A003586; a(n)=A003586(A014105(n)) for n<6. (End)

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..300
• Index entries for linear recurrences with constant coefficients, signature (6).

Crossrefs

Cf. A081341, A125682 ((6^n-1)*3/5), A005053 (expand (1-2x)/(1-5x)), A164346 (3*4^n), A169634 (3*7^n), A103333 (expand (1-5x)/(1-8x)).

Programs

Magma

[ 3*6^n: n in [0..19] ];

Mathematica

3*6^Range[0, 25] (* Paolo Xausa, Jan 17 2025 *)

PARI

a(n)=3*6^n \\ Charles R Greathouse IV, Oct 16 2015

Formula

a(n) = 6*a(n-1) for n > 0; a(0) = 3.

G.f.: 3/(1-6*x).