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 A056337 #9 Aug 22 2017 20:53:09 %S A056337 0,0,1,4,15,49,160,498,1544,4715,14356,43420,131145,394990,1188564, %T A056337 3572400,10732065,32224216,96733636,290317660,871200664,2614083394, %U A056337 7843255300,23531731530,70599259170,211805771345 %N A056337 Number of primitive (aperiodic) reversible string structures with n beads using exactly three different colors. %C A056337 A string and its reverse are considered to be equivalent. Permuting the colors will not change the structure. %D A056337 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 A056337 A056332(n)-A056331(n). %Y A056337 Column 3 of A276544. %Y A056337 Cf. A056319. %K A056337 nonn %O A056337 1,4 %A A056337 _Marks R. Nester_