A174581 Let J_n be an n X n all-1's matrix, I = I_n the n X n identity matrix and P = P_n the incidence matrix of the cycle (1,2,3,...,n). Then a(n) is the number of (0,1) n X n matrices A <= J_n - I - P - P^2 with exactly two 1's in every row and column.

0, 1, 20, 1266, 102574, 9746472

Offset

4,3

References

V. S. Shevelev, Development of the rook technique for calculating the cyclic indicators of (0,1)-matrices, Izvestia Vuzov of the North-Caucasus region, Nature sciences 4 (1996), 21-28 (in Russian).

S. E. Grigorchuk, V. S. Shevelev, An algorithm of computing the cyclic indicator of couples discordant permutations with restricted position, Izvestia Vuzov of the North-Caucasus region, Nature sciences 3 (1997), 5-13 (in Russian).

Links

Table of n, a(n) for n=4..9.

Crossrefs

Cf. A001499, A007107, A082491, A000186, A174564, A174580.

Sequence in context: A359645 A001451 A093598 * A153469 A160253 A338961

Adjacent sequences: A174578 A174579 A174580 * A174582 A174583 A174584

Keyword

nonn,more,uned

Author

Vladimir Shevelev, Mar 23 2010

Status

approved