%I A006230 M4902
%S A006230 1,13,73,301,1081,3613,11593,36301,111961,342013,1038313,3139501,
%T A006230 9467641,28501213,85700233,257493901,773268121,2321377213,6967277353,20908123501
%N A006230 Bitriangular permutations.
%D A006230 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006230 S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques 
               Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 
               1992.
%D A006230 I. Kaplansky and J. Riordan, The problem of the rooks and its applications, 
               Duke Math. J., 13 (1946), 259-268.
%H A006230 S. Plouffe, <a href="http://www.lacim.uqam.ca/%7Eplouffe/articles/MasterThesis.pdf">
               Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures</
               a>, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 
               1992.
%H A006230 S. Plouffe, <a href="http://www.lacim.uqam.ca/%7Eplouffe/articles/FonctionsGeneratrices.pdf">
               1031 Generating Functions and Conjectures</a>, Universit\'{e} du 
               Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
%F A006230 a(n) = 12*S(n-2) + 1, with S(n)=A000392(n) the Stirling numbers of second 
               kind. - Ralf Stephan (ralf(AT)ark.in-berlin.de), Jul 07 2003
%p A006230 A006230:=-(z+1)*(6*z+1)/(z-1)/(3*z-1)/(2*z-1); [Conjectured by S. Plouffe 
               in his 1992 dissertation.]
%Y A006230 Sequence in context: A081586 A143008 A107963 this_sequence A066110 A020527 
               A146618
%Y A006230 Adjacent sequences: A006227 A006228 A006229 this_sequence A006231 A006232 
               A006233
%K A006230 nonn
%O A006230 4,2
%A A006230 N. J. A. Sloane (njas(AT)research.att.com).