A153795 5 times octagonal numbers: a(n) = 5*n*(3*n-2).

0, 5, 40, 105, 200, 325, 480, 665, 880, 1125, 1400, 1705, 2040, 2405, 2800, 3225, 3680, 4165, 4680, 5225, 5800, 6405, 7040, 7705, 8400, 9125, 9880, 10665, 11480, 12325, 13200, 14105, 15040, 16005, 17000, 18025, 19080, 20165, 21280

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

Formula

a(n) = 15*n^2 - 10*n = A000567(n)*5.

a(n) = 30*n + a(n-1) - 25 for n > 0, a(0) = 0. - Vincenzo Librandi, Aug 03 2010

From G. C. Greubel, Aug 29 2016: (Start)

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

G.f.: 5*x*(1 + 5*x)/(1 - x)^3.

E.g.f.: 5*x*(1 + 3*x)*exp(x). (End)

Mathematica

Table[5 * n * (3 * n - 2) , {n, 0, 25}] (* or *) LinearRecurrence[{3, -3, 1}, {0, 5, 40}, 25] (* G. C. Greubel, Aug 28 2016 *)

Prog

(PARI) a(n)=5*n*(3*n-2) \\ Charles R Greathouse IV, Jun 17 2017

Crossrefs

Cf. A000567, A153794, A153796.

Sequence in context: A371557 A222366 A029538 * A015874 A244725 A319098

Adjacent sequences: A153792 A153793 A153794 * A153796 A153797 A153798

Keyword

nonn,easy

Author

Omar E. Pol, Jan 20 2009

Status

approved