OFFSET
1,1
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
a(n) = 3*a(n-1) -3*a(n-2) +a(n-3).
G.f.: x*(52 +2570*x +1428*x^2)/(1-x)^3.
E.g.f.: -1428 + (1428 - 1376*x + 2025*x^2)*exp(x). - G. C. Greubel, Jan 28 2022
MATHEMATICA
LinearRecurrence[{3, -3, 1}, {52, 2726, 9450}, 40]
PROG
(Magma) I:=[52, 2726, 9450]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..40]];
(PARI) a(n)=2025*n^2-3401*n+1428 \\ Charles R Greathouse IV, Dec 23 2011
(Sage) [(81*n -68)*(25*n -21) for n in (1..40)] # G. C. Greubel, Jan 28 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 17 2009
STATUS
approved