This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A074728 #8 Aug 24 2017 12:36:56
%S A074728 1,3,10,39,176,903,5174,32623,223792,1655463,13110758,110510007,
%T A074728 986490272,9287036671,91872460702,952034494431,10305790066208,
%U A074728 116254839687543,1363631057783942,16599343732844455,209328335818064176,2730323984395924623,36780442970179975646
%N A074728 a(n) = Sum_{k=1..n} k^(n-k)*binomial(n,k-1).
%F A074728 E.g.f.: (exp(x*exp(x))-exp(x))/x.
%t A074728 Table[Sum[k^(n-k) Binomial[n,k-1],{k,n}],{n,30}] (* _Harvey P. Dale_, Mar 19 2013 *)
%Y A074728 Cf. A000248.
%K A074728 nonn
%O A074728 1,2
%A A074728 _Vladeta Jovovic_, Sep 05 2002