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 A056315 #10 Aug 22 2017 20:53:08 %S A056315 4,6,36,126,540,2034,8316,32760,131544,524250,2099196,8388450, %T A056315 33562620,134217594,536903100,2147483520,8590065660,34359735816, %U A056315 137439477756,549755813250,2199025344348,8796093020154 %N A056315 Number of primitive (aperiodic) reversible strings with n beads using a maximum of four different colors. %C A056315 A string and its reverse are considered to be equivalent. %D A056315 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 A056315 Sum mu(d)*A032121(n/d) where d|n. %Y A056315 Column 4 of A284871. %Y A056315 Cf. A045625, A056314. %K A056315 nonn %O A056315 1,1 %A A056315 _Marks R. Nester_