A139581 a(n) = n*(2*n + 19).

0, 21, 46, 75, 108, 145, 186, 231, 280, 333, 390, 451, 516, 585, 658, 735, 816, 901, 990, 1083, 1180, 1281, 1386, 1495, 1608, 1725, 1846, 1971, 2100, 2233, 2370, 2511, 2656, 2805, 2958, 3115, 3276, 3441, 3610, 3783, 3960, 4141

Offset

0,2

Links

Table of n, a(n) for n=0..41.

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

Formula

a(n) = 2*n^2 + 19*n.

a(n) = a(n-1) + 4*n + 17 (with a(0)=0). - Vincenzo Librandi, Nov 24 2010

From Elmo R. Oliveira, Nov 29 2024: (Start)

G.f.: x*(21 - 17*x)/(1-x)^3.

E.g.f.: exp(x)*x*(21 + 2*x).

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

Mathematica

Table[n(2n+19), {n, 0, 50}]  (* Harvey P. Dale, Jan 26 2011 *)

Prog

(PARI) a(n)=n*(2*n+19) \\ Charles R Greathouse IV, Jun 17 2017

Crossrefs

Cf. A014105, A014106, A033537, A130861, A139576, A139577, A139578, A139579, A139580.

Sequence in context: A199767 A044098 A044479 * A250777 A327302 A156966

Adjacent sequences: A139578 A139579 A139580 * A139582 A139583 A139584

Keyword

easy,nonn

Author

Omar E. Pol, May 19 2008

Status

approved