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 A090539 #22 Sep 27 2018 05:06:33
%S A090539 0,1,4,11,28,62,137,278,561,1080,2051,3778,6885,12255,21589,37409,
%T A090539 64160,108612,182234,302461,497997,812579,1316225,2115608,3378239,
%U A090539 5357855,8447086,13237631,20632630,31985504,49339795,75738099,115731636,176055280,266697522
%N A090539 Total number of parts equal to 1 in all plane partitions of n.
%H A090539 Alois P. Heinz, <a href="/A090539/b090539.txt">Table of n, a(n) for n = 0..50</a>
%t A090539 Table[Count[Flatten[planepartitions[k]], 1], {k, 17}]
%o A090539 (PARI) A090539(n)=A092288(n,1) \\ _M. F. Hasler_, Sep 26 2018
%Y A090539 Column k=1 of A092288.
%Y A090539 Cf. A066633, A000219, A091298.
%K A090539 nonn
%O A090539 0,3
%A A090539 _Wouter Meeussen_, Feb 01 2004
%E A090539 a(18)-a(27) from _Vaclav Kotesovec_, May 05 2018
%E A090539 a(28)-a(34) from _Alois P. Heinz_, Sep 24 2018