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 A026969 #8 Oct 20 2019 16:23:11
%S A026969 1,10,75,372,1796,7796,33352,138790,571995,2334558,9473195,38258984,
%T A026969 153981400,618042736,2475405456,9897862062,39523226642,157650156506,
%U A026969 628287555844,2502170730172,9959281642416,39622214018100,157575049910690,626477638980782,2490112612092175
%N A026969 a(n) = Sum_{k=0..n-3} T(n,k) * T(n,k+3), with T given by A026637.
%K A026969 nonn
%O A026969 3,2
%A A026969 _Clark Kimberling_
%E A026969 More terms from _Sean A. Irvine_, Oct 20 2019