OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..5000
Sela Fried, Counting r X s rectangles in nondecreasing and Smirnov words, arXiv:2406.18923 [math.CO], 2024. See p. 5.
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
a(n) = (3*n^2 + 17*n)/2.
a(n) = 7*n + 3*A000217(n). - Reinhard Zumkeller, May 28 2008
a(n) = 3*n + a(n-1) + 7 (with a(0)=0). - Vincenzo Librandi, Aug 03 2010
G.f.: x*(10 - 7*x)/(1 - x)^3. - Arkadiusz Wesolowski, Dec 24 2011
E.g.f.: (1/2)*(3*x^2 + 20*x)*exp(x). - G. C. Greubel, Jul 17 2017
MATHEMATICA
Table[(3*n^2 + 17*n)/2, {n, 0, 50}] (* G. C. Greubel, Jul 17 2017 *)
PROG
(PARI) a(n)=n*(3*n+17)/2 \\ Charles R Greathouse IV, Jun 17 2017
(Magma) [n*(3*n + 17)/2: n in [0..70]]; // Wesley Ivan Hurt, Apr 21 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Omar E. Pol, May 22 2008
STATUS
approved