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 A056397 #10 Aug 22 2017 20:53:10 %S A056397 0,0,1,4,8,50,54,284,525,2370,2872,22748,21866,131750,298792,904918, %T A056397 1341518,10745090,10748218,72889084,145274556,522819590,713023210, %U A056397 5892634240,7059926605,35300985550,70604008204 %N A056397 Number of step shifted (decimated) sequence structures using exactly three different symbols. %C A056397 See A056371 for an explanation of step shifts. Permuting the symbols will not change the structure. %D A056397 M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2] %F A056397 A056392(n)-A056391(n). %Y A056397 Column 3 of A288620. %Y A056397 Cf. A056377. %K A056397 nonn %O A056397 1,4 %A A056397 _Marks R. Nester_