%I A069920
%S A069920 4,1008,8190720,2332005728256,23674927650073214976,
%T A069920 8618480376852061696039059456,112746432609478969278312620164116381696,
%U A069920 53053593891934168169788522401776516627950360068096
%N A069920 Noninvertible n X n matrices mod 6 (i.e. over the ring Z_6).
%F A069920 a(n) = 6^(n^2) - A065498(n)
%o A069920 (PARI) for(n=1,10,print1(6^(n^2)*(1-prod(k=1,n,(1-1/2^k)*(1-1/3^k))),
               ","))
%Y A069920 Cf. A065498, A069580.
%Y A069920 Sequence in context: A006030 A087365 A024059 this_sequence A013780 A139300 
               A004804
%Y A069920 Adjacent sequences: A069917 A069918 A069919 this_sequence A069921 A069922 
               A069923
%K A069920 nonn
%O A069920 1,1
%A A069920 Sharon Sela (sharonsela(AT)hotmail.com), May 05 2002
%E A069920 More terms from Benoit Cloitre (benoit7848c(AT)orange.fr), May 11 2002