%I A066383
%S A066383 1,2,7,42,386,4944,82160,1683218,40999516,1156626990,37060382822,
%T A066383 1328700402564,52676695500313,2287415069586304,107943308165833912,
%U A066383 5499354613856855290,300788453960472434648,17577197510240126035698
%N A066383 Sum_{k=0..n} C(n*(n+1)/2,k).
%Y A066383 Sequence in context: A131682 A158840 A038052 this_sequence A011802 A007065 
               A005130
%Y A066383 Adjacent sequences: A066380 A066381 A066382 this_sequence A066384 A066385 
               A066386
%K A066383 nonn
%O A066383 0,2
%A A066383 N. J. A. Sloane (njas(AT)research.att.com), Dec 23 2001