OFFSET
1,2
COMMENTS
Central terms of triangle A214604.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
G.f.: (1+14*x+3*x^2)/(1-x)^3. - Harvey P. Dale, Aug 29 2021
E.g.f.: -3 + (3 - 2*x + 9*x^2)*exp(x). - G. C. Greubel, Mar 09 2024
MATHEMATICA
Table[9n^2-11n+3, {n, 60}] (* or *) LinearRecurrence[{3, -3, 1}, {1, 17, 51}, 60] (* Harvey P. Dale, Aug 29 2021 *)
PROG
(Haskell)
a214660 n = (9 * n - 11) * n + 3
(PARI) a(n)=9*n^2-11*n+3 \\ Charles R Greathouse IV, Jun 17 2017
(Magma) [9*n^2-11*n+3: n in [1..60]]; // G. C. Greubel, Mar 09 2024
(SageMath) [9*n^2-11*n+3 for n in range(1, 61)] # G. C. Greubel, Mar 09 2024
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Reinhard Zumkeller, Jul 25 2012
STATUS
approved