OFFSET
0,2
LINKS
Paolo Xausa, Table of n, a(n) for n = 0..10000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
a(n) = 7*n^2 - n + 2, for n>3.
a(n) = 3*a(n-1)-3*a(n-2)+a(n-3) for n>6. G.f.: -(2*x^6 -x^5 -6*x^4 +5*x^3 +11*x^2 +2*x +1) / (x -1)^3. - Colin Barker, Jul 14 2013
EXAMPLE
5 squares are reachable after 1 move, from these you can reach 18 new squares more, so a(1)=5 and a(2)=23.
MATHEMATICA
LinearRecurrence[{3, -3, 1}, {1, 5, 23, 60, 110, 172, 248}, 50] (* Paolo Xausa, Jul 17 2024 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ralf Stephan, Sep 15 2004
EXTENSIONS
More terms from Colin Barker, Jul 14 2013
STATUS
approved