A377601 - OEIS

%I #37 Nov 07 2024 15:02:56

%S 0,0,4,1674,63062976,623360743125000,2670177736637149247308080,

%T 7363615666157189603982585462030330960,

%U 18165723931630806756964027928179555634194028453959680,53130688706387569792052442448845648519471103327391407016237759999637120

%N Number of permutations of the multiset {1^n, 2^n,..., n^n} excluding permutations where all objects of all types are contiguous.

%F a(n) = (n^2)!/(n!)^n - n!.

%F a(n) = A034841(n) - A000142(n).

%e For n=2, the multiset is {1,1,2,2} and the a(2)=4 permutations counted are 1212, 1221, 2112, 2121 (but neither 1122 nor 2211).

%Y Cf. A000142, A034841.

%K nonn,easy

%O 0,3

%A _Mohammad Bakhshandeh_, Nov 02 2024