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%I #18 Mar 30 2012 18:52:59
%S 6,9,12,13,17,18,20,36,24,25,26,27,30,31,32,54,33,34,35,36,37,38,39,
%T 40,41,42,44,45,48,49,52,72,78,81
%N Irregular triangle, read by rows, of the A185178(n) values of the permanent of an n X n (0,1)-matrix (n>=3) with exactly three 1's in each row and each column.
%D 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).
%H V. S. Shevelev, <a href="http://dx.doi.org/10.1007/BF01104103">Some problems of the theory of enumerating the permutations with restricted position</a>, Journal of Soviet Mathematics, 61 (4) (1992) 2272-2317 (see pp. 2307-2309).
%e Triangle begins:
%e 6
%e 9
%e 12, 13
%e 17, 18, 20, 36
%e 24, 25, 26, 27, 30, 31, 32, 54,
%e 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 44, 45, 48, 49, 52, 72, 78, 81
%Y Cf. A185178, A185177, A176211, A176212.
%K nonn,tabf,hard,more
%O 3,1
%A _Vladimir Shevelev_, Feb 19 2011