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 A054117 #14 Sep 19 2017 07:46:57 %S A054117 1,6,30,150,870,5910,46230,409110,4037910,43954710,522956310, %T A054117 6749977110,93928268310,1401602636310,22324392524310,378011820620310, %U A054117 6780385526348310 %N A054117 T(n,n-2), array T as in A054115. %H A054117 Jan Kneissler, <a href="https://arxiv.org/abs/q-alg/9706022">The number of primitive Vassiliev invariants of degree up to 12</a>, arXiv:q-alg/9706022, 1997; Section 6.1. %F A054117 Conjecture: a(n) -(n+1)*a(n-1) +n*a(n-2)=0. - _R. J. Mathar_, Jun 13 2013 %K A054117 nonn %O A054117 2,2 %A A054117 _Clark Kimberling_