OFFSET
3,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 3..1000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
Numerators of sequence a[n,n-2] in (a[i,j])^4 where a[i,j] = binomial(i-1, j-1)/2^(i-1) if j<=i, 0 if j>i.
G.f.: 225*(1 - 3*x + 3*x^2)/(1 - x)^3. - Vincenzo Librandi, Dec 29 2012
a(3)=225, a(4)=675, a(5)=1350, a(n) = 3*a(n-1) -3*a(n-2) +a(n-3). - Harvey P. Dale, Feb 01 2013
MAPLE
seq(225*binomial(n-1, 2), n=3..50); # G. C. Greubel, May 14 2021
MATHEMATICA
Table[225 (n-1) (n-2)/2, {n, 3, 50}] (* Vincenzo Librandi, Dec 29 2012 *)
LinearRecurrence[{3, -3, 1}, {225, 675, 1350}, 40] (* Harvey P. Dale, Feb 01 2013 *)
PROG
(Magma) [225*(n-1)*(n-2)/2: n in [3..50]]; // Vincenzo Librandi, Dec 29 2012
(PARI) a(n)=225*(n-1)*(n-2)/2 \\ Charles R Greathouse IV, Jun 17 2017
(Sage) [225*binomial(n-1, 2) for n in (3..50)] # G. C. Greubel, May 14 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved