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 A056409 #6 Aug 22 2017 20:53:11 %S A056409 0,0,0,0,1,9,26,299,1183,10700,24736,349232,626053,6680953,26364609, %T A056409 137246955,353304459,4826416835,8199440662,93679518802,315943737305, %U A056409 1913783049725,4382586624256,60629067426943 %N A056409 Number of primitive (aperiodic) step shifted (decimated) sequence structures using exactly five different symbols. %C A056409 See A056371 for an explanation of step shifts. Permuting the symbols will not change the structure. %D A056409 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 A056409 A056404(n)-A056403(n). %Y A056409 Cf. A056389. %K A056409 nonn %O A056409 1,6 %A A056409 _Marks R. Nester_