A153449 11 times pentagonal numbers: 11*n*(3n-1)/2.

0, 11, 55, 132, 242, 385, 561, 770, 1012, 1287, 1595, 1936, 2310, 2717, 3157, 3630, 4136, 4675, 5247, 5852, 6490, 7161, 7865, 8602, 9372, 10175, 11011, 11880, 12782, 13717, 14685, 15686, 16720, 17787, 18887, 20020, 21186, 22385

Offset: 0

Author

Omar E. Pol, Dec 26 2008

Keywords

• easy
• nonn

Links

• Ivan Panchenko, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

Crossrefs

Cf. A000326.

Programs

Mathematica

Table[11*n*(3n-1)/2, {n,0,25}] (* or *) LinearRecurrence[{3,-3,1},{0,11,55},25] (* G. C. Greubel, Aug 21 2016 *)

PARI

a(n)=11*n*(3*n-1)/2 \\ Charles R Greathouse IV, Jun 17 2017

Formula

a(n) = (33*n^2 - 11*n)/2 = A000326(n)*11.

a(n) = 33*n + a(n-1) - 22 (with a(0)=0). - Vincenzo Librandi, Aug 03 2010

G.f.: 11*x*(1+2*x)/(1-x)^3. - Colin Barker, Feb 21 2012

From G. C. Greubel, Aug 21 2016: (Start)

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

E.g.f.: (11/2)*x*(2 + 3*x)*exp(x). (End)