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A174581 Let J_n be 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. 3
0, 1, 20, 1266, 102574, 9746472 (list; graph; refs; listen; history; text; internal format)
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

A001499 A007107 A082491 A000186 A174564 A174580

Sequence in context: A294191 A001451 A093598 * A153469 A160253 A274645

Adjacent sequences:  A174578 A174579 A174580 * A174582 A174583 A174584

KEYWORD

nonn,uned

AUTHOR

Vladimir Shevelev, Mar 23 2010

STATUS

approved

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Last modified May 31 10:42 EDT 2020. Contains 334748 sequences. (Running on oeis4.)