A245804 a(n) = 2*3^n - 3*2^n.

-1, 0, 6, 30, 114, 390, 1266, 3990, 12354, 37830, 115026, 348150, 1050594, 3164070, 9516786, 28599510, 85896834, 257887110, 774054546, 2322950070, 6970423074, 20914414950, 62749536306, 188261191830, 564808741314, 1694476555590, 5083530330066, 15250792316790

Offset: 0

Author

Vincenzo Librandi, Aug 03 2014

Keywords

• sign
• easy

Comments

Essentially 2 * A210448. - Joerg Arndt, Aug 03 2014

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (5,-6).

Crossrefs

Cf. A007283, A008776.

Programs

Magma

[2*3^n-3*2^n: n in [0..40]];

Magma

I:=[-1,0]; [n le 2 select I[n] else 5*Self(n-1)-6*Self(n-2): n in [1..30]];

Mathematica

CoefficientList[Series[(-1 + 5 x)/((1 - 2 x) (1 - 3 x)), {x, 0, 30}], x]
Table[(2 3^n - 3 2^n), {n, 0, 30}] (* Vincenzo Librandi, Aug 04 2014 *)

Formula

G.f.: (-1 +5*x)/((1-2*x)(1-3*x)).

a(n) = 5*a(n-1) -6*a(n-2) for n>1.

a(n) = A008776(n) - A007283(n). - Michel Marcus, Aug 03 2014