%I A001046 M1811 N0717
%S A001046 1,1,2,7,44,447,6749,142176,3987677,143698548,6470422337,356016927083,
%T A001046 23503587609815,1833635850492653,166884365982441238,
%U A001046 17524692064006822643,2103129932046801158398,286043195450428964364771
%N A001046 a(n) = n(n-1)a(n-1)/2 + a(n-2).
%D A001046 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A001046 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%e A001046 a(4) = 4*3*7/2 + 2 = 44.
%Y A001046 Cf. A001052.
%Y A001046 Sequence in context: A000155 A077045 A128579 this_sequence A158257 A153522 
               A107354
%Y A001046 Adjacent sequences: A001043 A001044 A001045 this_sequence A001047 A001048 
               A001049
%K A001046 nonn,easy
%O A001046 0,3
%A A001046 N. J. A. Sloane (njas(AT)research.att.com).
%E A001046 More terms from James A. Sellers (sellersj(AT)math.psu.edu), Oct 05 2000