0,2

D. E. Knuth, Nonattacking kings on a chessboard, 1994.

H. S. Wilf, The problem of the kings, Elec. J. Combin. 2, 1995.

G.f.: (1+13x-52x^2-20x^3+60x^4-20x^5)/((1-3x)(1-4x)^2(1-4x+2x^2)^2).

(PARI) a(n)=polcoeff((1+13*x-52*x^2-20*x^3+60*x^4-20*x^5)/((1-3*x)*(1-4*x)^2*(1-4*x+2*x^2)^2)+x*O(x^n), n)

Cf. A001787, A061593.

Equals 231*A002697(n+1) - 2608*A000302(n) - 384*A000244(n) + 1103*A007070(n-1) + 780*A006012(n+1) + (n+1)*(17*A048580(n) + 12*A007070(n+1)).

Sequence in context: A128798 A086942 A068548 this_sequence A125116 A145217 A125444

Adjacent sequences: A061591 A061592 A061593 this_sequence A061595 A061596 A061597

nonn

Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), May 22 2001