A182462 a(n) = 3a(n-1) - 2a(n-2) with a(0)=20 and a(1)=50.

20, 50, 110, 230, 470, 950, 1910, 3830, 7670, 15350, 30710, 61430, 122870, 245750, 491510, 983030, 1966070, 3932150, 7864310, 15728630, 31457270, 62914550, 125829110, 251658230, 503316470, 1006632950, 2013265910, 4026531830, 8053063670, 16106127350

Offset: 0

Author

Odimar Fabeny, Apr 30 2012

Keywords

• easy
• nonn

Comments

Number of vertices into building blocks of 3d objects with 5 vertices.

Examples

			a(0) = 5+10+5;
a(1) = 5+10+20+10+5;
a(2) = 5+10+20+40+20+10+5;
a(3) = 5+10+20+40+80+40+20+10+5.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (3, -2).

Crossrefs

Cf. A000045, A028399, A038578, A089143, A173033, A182461, A182464, A182465, A182466, A182467.

Programs

Mathematica

CoefficientList[Series[-((10 (x - 2))/(2 x^2 - 3 x + 1)), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 02 2014 *)

Formula

a(n) = a(n-1)*2 + 10.

a(n) = 10*A153893(n). - Michel Marcus, Jun 01 2014

G.f.: -((10*(x - 2))/(2*x^2 - 3*x + 1)). - Vincenzo Librandi, Jun 02 2014