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 A056416 #6 Aug 22 2017 20:53:11 %S A056416 0,0,1,6,9,56,51,258,380,1500,1611,12298,10245,57108,121721,346146, %T A056416 474489,3589534,3397143,21984804,41570773,142619388,186027579, %U A056416 1476414178,1694455320,8146633638,15690141155 %N A056416 Number of step cyclic shifted sequences using exactly three different symbols. %C A056416 See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. %D A056416 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 A056416 A056411(n)-3*A002729(n)+3. %Y A056416 Cf. A056411. %K A056416 nonn %O A056416 1,4 %A A056416 _Marks R. Nester_