OFFSET
0,1
LINKS
FORMULA
a(n) = ceiling(a(n-1)^2/a(n-2)), a(0) = 6, a(1) = 15.
a(n) = floor(a(n-1)^2/a(n-2)+1), a(0) = 6, a(1) = 15.
Conjectures: (Start)
G.f.: (6 - 3*x - x^2 - 2*x^3 + x^4 + 3*x^5 - 5*x^6)/((1 - x)*(1 - 2 x - x^2 - x^3 - 2*x^6)).
a(n) = 3*a(n-1) - a(n-2) - a(n-4) + 2*a(n-6) - 2*a(n-7). (End)
MATHEMATICA
RecurrenceTable[{a[0] == 6, a[1] == 15, a[n] == Ceiling[a[n - 1]^2/a[n - 2]]}, a, {n, 28}]
RecurrenceTable[{a[0] == 6, a[1] == 15, a[n] == Floor[a[n - 1]^2/a[n - 2] + 1]}, a, {n, 28}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ilya Gutkovskiy, Sep 29 2016
STATUS
approved