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 A056406 #6 Aug 22 2017 20:53:11 %S A056406 0,1,2,4,5,16,13,42,49,133,107,600,351,1385,2164,4416,4115,22043, %T A056406 14601,67872,88360,209827,190745,1074534,839122,2796647,3730532, %U A056406 11275300,9587579,67193198,35792567 %N A056406 Number of primitive (aperiodic) step shifted (decimated) sequence structures using exactly two different symbols. %C A056406 See A056371 for an explanation of step shifts. Permuting the symbols will not change the structure. Identical to A056401 for n>1. %D A056406 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 A056406 A056401(n)-A000007(n-1). %Y A056406 Cf. A056386. %K A056406 nonn %O A056406 1,3 %A A056406 _Marks R. Nester_