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 A145073 #11 Mar 30 2012 18:37:14
%S A145073 1,2,7,44,325,3110,34258,436304,6246439,99637730,1747851787,
%T A145073 33469239848,694321125511,15513919320368,371408549270425,
%U A145073 9484764686963792,257355204923817028,7393783957451330630,224224270472995407877
%N A145073 Coefficient of x^(3^n) in Q(x)^(n+1), where Q(x) = Sum_{k>=0} (x^(3^k) + x^(2*3^k)).
%o A145073 (PARI) { a(n) = local( Q = sum(j=0,n,x^(3^j)+x^(2*3^j)) + O(x^(3^n+1)) ); polcoeff(Q^(n+1),3^n) }
%Y A145073 Cf. A007178, A145074, A145075, A145076.
%K A145073 nonn
%O A145073 0,2
%A A145073 _Paul D. Hanna_, Oct 09 2008
%E A145073 a(10)-a(12) from _Alois P. Heinz_, Apr 28 2009
%E A145073 a(13)-a(18) from _Max Alekseyev_, Dec 18 2011