%I A006541 M4920
%S A006541 1,1,13,4683,102247563,230283190977853,81124824998504073881821,
%T A006541 6297562064950066033518373935334635,
%U A006541 144199280951655469628360978109406917583513090155
%N A006541 Number of dissimilarity relations on an n-set.
%D A006541 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006541 M. Schader, Hierarchical analysis: classification with ordinal object 
               dissimilarities, Metrika, 27 (1980), 127-132.
%F A006541 Sum_{i=0..m-1} (m-i)!*Stirling2(m, m-i), where m = n(n-1)/2.
%Y A006541 Cf. A005121.
%Y A006541 A000670(n(n-1)/2).
%Y A006541 Sequence in context: A094316 A057842 A023345 this_sequence A103857 A032463 
               A060887
%Y A006541 Adjacent sequences: A006538 A006539 A006540 this_sequence A006542 A006543 
               A006544
%K A006541 nonn,nice,easy
%O A006541 1,3
%A A006541 N. J. A. Sloane (njas(AT)research.att.com).
%E A006541 More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jan 19 2000