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 A056415 #10 Aug 22 2017 20:53:11 %S A056415 0,1,2,4,4,11,8,22,20,43,28,156,72,243,366,691,520,2635,1608,7384, %T A056415 8866,19399,16768,94482,67560,216273,277532,815556,662368,4500265, %U A056415 2311468,8466187,13045106,31593283,40937604,159772174,103197488,401913695 %N A056415 Number of step cyclic shifted sequences using exactly two different symbols. %C A056415 See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. %D A056415 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 A056415 a(n) = A002729(n) - 2. %Y A056415 Cf. A002729. %K A056415 nonn %O A056415 1,3 %A A056415 _Marks R. Nester_ %E A056415 Added more terms (from A002729), _Joerg Arndt_, Aug 27 2014