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 A056387 #6 Aug 22 2017 20:53:10 %S A056387 0,0,3,21,39,285,309,1638,3099,14109,17157,135918,130995,789819, %T A056387 1791447,5425938,8047839,64463793,64486017,437310162,871626729, %U A056387 3136882659,4278115101,35355495078,42359479599 %N A056387 Number of primitive (aperiodic) step shifted (decimated) sequences using exactly three different symbols. %C A056387 See A056371 for an explanation of step shifts. %D A056387 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 A056387 Sum mu(d)*A056377(n/d) where d|n. %K A056387 nonn %O A056387 1,3 %A A056387 _Marks R. Nester_