cp's OEIS Frontend

A222204 Write n=3i+j, 0<=j<3; a(n) = number of ways to cover the r X s grid graph by vertex disjoint cycles, where (r,s) = (2i+2, 2i+2) (if j=0), (2i+2, 2i+3) (if j=1) or (2i+3, 2i+4) (if j=2).

%I A222204 #9 Jan 01 2019 06:52:42
%S A222204 1,1,3,18,54,1140,13903,99051,13049563,360783593,6044482889,
%T A222204 4738211572702,303872744726644,11986520595161863,54755153078468134960,
%U A222204 8217125138015950451626,764291947227525464744293,20119942924108379011391597989,7095967027221343377167292602835,1558052539448513320447263528275071
%N A222204 Write n=3i+j, 0<=j<3; a(n) = number of ways to cover the r X s grid graph by vertex disjoint cycles, where (r,s) = (2i+2, 2i+2) (if j=0), (2i+2, 2i+3) (if j=1) or (2i+3, 2i+4) (if j=2).
%C A222204 An interleaving of A222202 and A222203.
%H A222204 Peter Tittmann, <a href="http://www.htwm.de/~peter/research/enumeration.html">Enumeration in graphs: counting Hamiltonian cycles</a> [Broken link?]
%H A222204 Peter Tittmann, <a href="http://web.archive.org/web/20101127064650/https://www.staff.hs-mittweida.de/~peter/research/enumeration.html">Enumeration in graphs: counting Hamiltonian cycles</a> [Backup copy of top page only, on the Internet Archive]
%Y A222204 Cf. A222202, A222203.
%K A222204 nonn
%O A222204 0,3
%A A222204 _N. J. A. Sloane_, Feb 14 2013