OFFSET
1,2
COMMENTS
Zebra is a (fairy chess) leaper [2,3].
REFERENCES
Christian Poisson, Echecs et mathematiques, Rex Multiplex 29/1990, p. 829.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Vaclav Kotesovec, Number of ways of placing non-attacking queens and kings on boards of various sizes
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
a(n) = (n^4 - 9*n^2 + 40*n - 48)/2, n >= 2. (Christian Poisson, 1990)
G.f.: 2*x^2*(3+3*x-4*x^2+8*x^3-4*x^4)/(1-x)^5. - Vaclav Kotesovec, Mar 25 2010
E.g.f.: (1/2)*(16*(3+x) + (-48 + 32*x - 2*x^2 + 6*x^3 + x^4)*exp(x)). - G. C. Greubel, Apr 19 2022
MATHEMATICA
CoefficientList[Series[2x(3+3*x-4*x^2+8*x^3-4*x^4)/(1-x)^55, {x, 0, 40}], x] (* Vincenzo Librandi, May 26 2013 *)
PROG
(Magma) [n eq 1 select 0 else (n^4 -9*n^2 +40*n -48)/2: n in [1..50]]; // G. C. Greubel, Apr 19 2022
(SageMath) [(n^4 -9*n^2 +40*n -48 +16*bool(n==1))/2 for n in (1..50)] # G. C. Greubel, Apr 19 2022
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vaclav Kotesovec, Jan 26 2010
STATUS
approved