cp's OEIS Frontend

A377601 Number of permutations of the multiset {1^n, 2^n,..., n^n} excluding permutations where all objects of all types are contiguous.

%I A377601 #37 Nov 07 2024 15:02:56
%S A377601 0,0,4,1674,63062976,623360743125000,2670177736637149247308080,
%T A377601 7363615666157189603982585462030330960,
%U A377601 18165723931630806756964027928179555634194028453959680,53130688706387569792052442448845648519471103327391407016237759999637120
%N A377601 Number of permutations of the multiset {1^n, 2^n,..., n^n} excluding permutations where all objects of all types are contiguous.
%F A377601 a(n) = (n^2)!/(n!)^n - n!.
%F A377601 a(n) = A034841(n) - A000142(n).
%e A377601 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 A377601 Cf. A000142, A034841.
%K A377601 nonn,easy
%O A377601 0,3
%A A377601 _Mohammad Bakhshandeh_, Nov 02 2024