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 A056425 #6 Aug 22 2017 20:53:11 %S A056425 0,0,1,6,9,55,51,252,379,1491,1611,12236,10245,57057,121711,345888, %T A056425 474489,3589099,3397143,21983298,41570721,142617777,186027579, %U A056425 1476401628,1694455311,8146623393,15690140775 %N A056425 Number of primitive (period n) step cyclic shifted sequences using exactly three different symbols. %C A056425 See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. %D A056425 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 A056425 sum mu(d)*A056416(n/d) where d|n. %Y A056425 Cf. A056420. %K A056425 nonn %O A056425 1,4 %A A056425 _Marks R. Nester_