login
A139576
a(n) = n(2n+9).
6
0, 11, 26, 45, 68, 95, 126, 161, 200, 243, 290, 341, 396, 455, 518, 585, 656, 731, 810, 893, 980, 1071, 1166, 1265, 1368, 1475, 1586, 1701, 1820, 1943, 2070, 2201, 2336, 2475, 2618, 2765, 2916, 3071, 3230, 3393, 3560, 3731, 3906
OFFSET
0,2
FORMULA
a(n) = 2*n^2 + 9*n.
a(n) = a(n-1) + 4*n + 7 (with a(0)=0). - Vincenzo Librandi, Nov 24 2010
MATHEMATICA
s=0; lst={s}; Do[s+=n++ +11; AppendTo[lst, s], {n, 0, 7!, 4}]; lst (* Vladimir Joseph Stephan Orlovsky, Nov 19 2008 *)
Table[Sum[(2*i + n - 1), {i, 4, n}], {n, 3, 45}] (* Zerinvary Lajos, Jul 11 2009 *)
Table[n(2n+9), {n, 0, 50}] (* or *) LinearRecurrence[{3, -3, 1}, {0, 11, 26}, 50] (* Harvey P. Dale, Dec 18 2018 *)
PROG
(PARI) a(n)=n*(2*n+9) \\ Charles R Greathouse IV, Jun 17 2017
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, May 19 2008
STATUS
approved