%I A003409 M2814
%S A003409 3,9,30,105,378,1386,5148,19305,72930,277134,1058148,4056234,15600900,
%T A003409 60174900,232676280,901620585,3500409330,13612702950,53017895700,206769793230
%N A003409 3C(2n-1,n).
%D A003409 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A003409 C. Domb and A. J. Barrett, Enumeration of ladder graphs, Discrete Math. 
               9 (1974), 341-358.
%Y A003409 Equals 3 * A001700.
%Y A003409 Sequence in context: A119372 A145268 A148956 this_sequence A029651 A148957 
               A148958
%Y A003409 Adjacent sequences: A003406 A003407 A003408 this_sequence A003410 A003411 
               A003412
%K A003409 nonn
%O A003409 1,1
%A A003409 N. J. A. Sloane (njas(AT)research.att.com).