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A085905 Permanent of the symmetric n X n matrix M defined by M(i,j) = lcm(i,j) for 1 <= i,j <= n.

%I A085905 #16 Aug 20 2021 03:35:12
%S A085905 1,6,144,5952,772560,73664640,29745273600,8715934402560,
%T A085905 5068085799813120,2756328707949465600,4581860819083475558400,
%U A085905 2696083278990328597708800,7844679216026128507826995200
%N A085905 Permanent of the symmetric n X n matrix M defined by M(i,j) = lcm(i,j) for 1 <= i,j <= n.
%H A085905 Vaclav Kotesovec, <a href="/A085905/b085905.txt">Table of n, a(n) for n = 1..35</a>
%e A085905 a(2)=6 since the 2 by 2 matrix A with rows [1,2],[2,2] has permanent 1*2+2*2=6.
%p A085905 with(linalg): a:=(i,j)->lcm(i,j): seq(permanent(matrix(n,n,a)),n=1..14); # _Emeric Deutsch_, Feb 08 2005
%t A085905 a[n_] := Permanent[Table[LCM[i, j], {i, 1, n}, {j, 1, n}]]; Table[an = a[n]; Print["a(", n, ") = ", an]; an, {n, 1, 14}] (* _Jean-François Alcover_, Jan 07 2016 *)
%o A085905 (PARI) a(n)=matpermanent(matrix(n,n,r,c,lcm(r,c)));
%o A085905 vector(23,n,a(n)) \\ _Joerg Arndt_, Aug 15 2019
%Y A085905 Cf. A060238, A085244, A034444.
%K A085905 nonn
%O A085905 1,2
%A A085905 Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 16 2003
%E A085905 More terms from _Emeric Deutsch_, Feb 08 2005