OFFSET
0,6
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,3,-3,-3,3,1,-1).
FORMULA
a(n) = n*(n+1)*(n-1)/24 when n is odd, otherwise n*(n-2)*(n-4)/24.
G.f.: x^3*(2*x^2-x+1) / ((x-1)^4*(x+1)^3). - Colin Barker, Dec 24 2012
a(n) = n*(2*n^2-6*n+7-3*(2*n-3)*(-1)^n)/48. - Luce ETIENNE, Mar 19 2015
MATHEMATICA
LinearRecurrence[{1, 3, -3, -3, 3, 1, -1}, {0, 0, 0, 1, 0, 5, 2}, 50] (* Vincenzo Librandi, Dec 25 2012 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Sen-Peng Eu, Apr 05 2001
STATUS
approved