OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,2,1,-2,-3,-1).
FORMULA
a(n) = a(n-1) + 2*a(n-2) + a(n-3) - 2*a(n-4) - 3*a(n-5) - a(n-6), a(0) = 1, a(1) = 3, a(2) = 5, a(3) = 12, a(4) = 23, a(5) = 43.
G.f.: (2*x+1)/((x^2+x+1)*(x^2+x-1)^2).
CROSSREFS
KEYWORD
nonn,easy,changed
AUTHOR
Philippe Deléham, Aug 03 2012
STATUS
approved