OFFSET
1,2
COMMENTS
Zebra is a (fairy chess) leaper [2,3].
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Zebra Graph
Wikipedia, Zebra (chess)
FORMULA
a(n) = 4*(8*n^4 - 48*n^3 + 202*n^2 - 471*n + 507)/3, n>=9.
G.f.: -x * (4*x^12 -6*x^11 -2*x^10 -52*x^9 +160*x^8 -88*x^7 +2*x^6 -195*x^5 +473*x^4 -172*x^3 +66*x^2 +65*x +1) / (x-1)^5. - Vaclav Kotesovec, Mar 25 2010
MATHEMATICA
CoefficientList[Series[-(4 x^12 - 6 x^11 - 2 x^10 - 52 x^9 + 160 x^8 - 88 x^7 + 2 x^6 - 195 x^5 + 473 x^4 - 172 x^3 + 66 x^2 + 65 x + 1) / (x - 1)^5, {x, 0, 50}], x] (* Vincenzo Librandi, May 28 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vaclav Kotesovec, Jan 29 2010
STATUS
approved