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 A056446 #6 Aug 22 2017 20:53:12 %S A056446 0,0,0,1,1,11,13,82,162,929,1369,13718,16421,124689,355792,1356698, %T A056446 2555043,25933641,32931815,283329802,720489742,3308253663,5763641923, %U A056446 60874684720,93543112675,600086794431 %N A056446 Number of primitive (period n) step cyclic shifted sequence structures using exactly four different symbols. %C A056446 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 A056446 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 A056446 A056441(n)-A056440(n). %Y A056446 Cf. A056426. %K A056446 nonn %O A056446 1,6 %A A056446 _Marks R. Nester_