A059224 a(n) = 2^(n-3)*(n + 3)*(2*n - 3).

18, 70, 224, 648, 1760, 4576, 11520, 28288, 68096, 161280, 376832, 870400, 1990656, 4513792, 10158080, 22708224, 50462720, 111542272, 245366784, 537395200, 1172307968, 2548039680, 5519704064, 11920211968, 25669140480, 55129931776, 118111600640, 252463546368, 538481524736

Offset: 3

Author

N. J. A. Sloane, Jan 19 2001

Keywords

• nonn
• easy

Links

• Harry J. Smith, Table of n, a(n) for n = 3..200
• Index entries for linear recurrences with constant coefficients, signature (6,-12,8).

Crossrefs

A diagonal of triangle defined in A059226.

Programs

Maple

seq(2^(n-3)*(n+3)*(2*n-3), n = 3 .. 32); # Emeric Deutsch, Jun 27 2009

Mathematica

Table[2^(n-3)*(n + 3)*(2*n - 3), {n,3,50}] (* or *) LinearRecurrence[{6, -12, 8}, {18, 70, 224}, 25] (* G. C. Greubel, Dec 30 2016 *)

PARI

a(n) = { 2^(n - 3)*(n + 3)*(2*n - 3) } \\ Harry J. Smith, Jun 25 2009

Formula

G.f. = 2x^3*(9-19x+10x^2)/(1-2x)^3. - Emeric Deutsch, Jun 27 2009

From G. C. Greubel, Dec 30 2016: (Start)

a(n) = 6*a(n-1) - 12*a(n-2) + 8*a(n-3).

E.g.f.: (1/8)*((9 + 8*x - 10*x^2) - (9 - 10*x - 8*x^2)*exp(2*x)). (End)