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 A056445 #6 Aug 22 2017 20:53:12 %S A056445 0,0,1,2,3,13,11,50,71,271,281,2139,1741,9639,20452,58019,79293, %T A056445 599367,566739,3667942,6931300,23775873,31008623,246106846,282422549, %U A056445 1357817329,2615067894,11358094490 %N A056445 Number of primitive (period n) step cyclic shifted sequence structures using exactly three different symbols. %C A056445 See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. Permuting the symbols will not change the structure. %D A056445 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 A056445 A056440(n)-A056439(n). %Y A056445 Cf. A056425. %K A056445 nonn %O A056445 1,4 %A A056445 _Marks R. Nester_