A144312 a(n) = 5*n*(5*n + 1)/2.

0, 15, 55, 120, 210, 325, 465, 630, 820, 1035, 1275, 1540, 1830, 2145, 2485, 2850, 3240, 3655, 4095, 4560, 5050, 5565, 6105, 6670, 7260, 7875, 8515, 9180, 9870, 10585, 11325, 12090, 12880, 13695, 14535, 15400, 16290, 17205, 18145, 19110, 20100

Offset

0,2

Links

Stefano Spezia, Table of n, a(n) for n = 0..10000

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

Formula

a(n) = A000217(5*n).

a(n) = a(n-1) + 25*n - 10 (with a(0) = 0). - Vincenzo Librandi, Nov 25 2010

From Stefano Spezia, Jun 12 2021: (Start)

O.g.f.: 5*x*(3 + 2*x)/(1 - x)^3.

E.g.f.: 5*exp(x)*x*(6 + 5*x)/2.

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

Prog

(PARI) a(n)=5*n*(5*n+1)/2 \\ Charles R Greathouse IV, Jun 17 2017

Crossrefs

Cf. A000217, A014105, A033585, A081266.

Sequence in context: A043972 A226196 A179741 * A062025 A211797 A172436

Adjacent sequences: A144309 A144310 A144311 * A144313 A144314 A144315

Keyword

nonn,easy

Author

Reinhard Zumkeller, Sep 17 2008

Status

approved