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 A027100 #7 Oct 23 2019 20:14:13
%S A027100 1,1,2,3,3,6,8,11,17,25,34,53,76,107,163,236,335,506,734,1050,1575,
%T A027100 2290,3291,4915,7156,10321,15362,22392,32381,48075,70135,101633,
%U A027100 150591,219843,319101,472067,689535,1002196,1480703,2163798,3148403,4646697,6792904,9892961,14588004
%N A027100 Diagonal sum of left justified array T given by A027082.
%F A027100 a(n) = Sum_{k=0..n} A027052(n-k, k). - _Sean A. Irvine_, Oct 23 2019
%K A027100 nonn
%O A027100 0,3
%A A027100 _Clark Kimberling_
%E A027100 More terms from _Sean A. Irvine_, Oct 23 2019