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A062740
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Number of connected labeled graphs with loops.
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51
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1, 2, 4, 32, 608, 23296, 1709056, 238880768, 64396439552, 33943701028864, 35324404321091584, 72994114660256448512, 300460426062916084563968, 2468021884106048216693211136, 40495494119922790159005962469376, 1328011048967552376327692463141552128
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OFFSET
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0,2
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LINKS
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FORMULA
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E.g.f.: 1+log( Sum_{n >= 0} 2^binomial(n+1, 2)*x^n/n! ).
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MAPLE
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logtr:= proc(p) local b; b:= proc(n) option remember; if n=0 then 1 else p(n)- add(k *binomial(n, k) *p(n-k) *b(k), k=1..n-1)/n fi end end:
a:= logtr(n-> 2^binomial(n+1, 2)):
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MATHEMATICA
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nn=14; g=Sum[2^Binomial[n, 2](2x)^n/n!, {n, 0, nn}]; Range[0, nn]!CoefficientList[Series[Log[g]+1, {x, 0, nn}], x] (* Geoffrey Critzer, Feb 01 2014 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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