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Irregular triangular array read by rows: T(n,k) is the number of 2-colored simple labeled graphs on n nodes that have exactly k edges, 0<=k<=A002620(n), n>=1.
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%I #19 Aug 21 2014 23:27:43

%S 0,2,2,6,12,6,14,48,60,32,6,30,160,360,440,310,120,20,62,480,1680,

%T 3480,4680,4212,2520,960,210,20,126,1344,6720,20720,43680,66108,73514,

%U 60480,36540,15820,4662,840,70,254,3584,24192,103040,308560,686784,1172976,1565888,1649340,1373680,900592,459312,178416,50960,10080,1232,70,510,9216,80640,451584,1808352,5491584,13102992,25128720,39312018,50638224,53981928,47698560,34869744,20975472,10281672,4044096,1246644,290304,48048,5040,252

%N Irregular triangular array read by rows: T(n,k) is the number of 2-colored simple labeled graphs on n nodes that have exactly k edges, 0<=k<=A002620(n), n>=1.

%C Row sums = A213441.

%H R. C. Read, <a href="http://dx.doi.org/10.4153/CJM-1960-035-0">The number of k-colored graphs on labelled nodes</a>, Canad. J. Math., 12 (1960), 410—414

%F E.g.f.: Sum_{n>=1} (exp(1 + y)^n*x - 1)*x^n/n!.

%e 0,

%e 2, 2,

%e 6, 12, 6,

%e 14, 48, 60, 32, 6,

%e 30, 160, 360, 440, 310, 120, 20,

%e 62, 480, 1680, 3480, 4680, 4212, 2520, 960, 210, 20

%t nn=10;f[x_]:=Sum[x^n/(n!*(1+y)^(n^2/2)),{n,0,nn}];CoefficientList[Table[n!*(1+y)^(n^2/2),{n,0,nn}]CoefficientList[Series[(f[x]-1)^2,{x,0,nn}],x]//Simplify//Expand,y]//Grid

%K nonn,tabf

%O 1,2

%A _Geoffrey Critzer_, Aug 08 2014