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A185178
Number of different values of the permanent of an n X n (0,1)-matrix with exactly three 1's in each row and each column.
4
1, 1, 2, 4, 8, 18
OFFSET
3,3
COMMENTS
The values a(n) are unknown for n>=9.
REFERENCES
V. I. Bolshakov, On spectrum of permanent on Lambda_n^k, Proc. of Seminar on Discrete Math. and Appl., Moscow State Univ. (1986), 65-73 (in Russian).
LINKS
V. S. Shevelev, Some problems of the theory of enumerating the permutations with restricted position, Journal of Soviet Mathematics, 61 (4) (1992) 2272-2317 (see pp. 2307-2309).
CROSSREFS
Cf. A185177 (values of the permanent), A176211, A176212.
Sequence in context: A372543 A255999 A171719 * A351471 A229718 A246469
KEYWORD
nonn,bref,hard,more
AUTHOR
Vladimir Shevelev, Feb 19 2011
STATUS
approved