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 A045632 #12 Aug 28 2019 08:16:15 %S A045632 1,1,1,2,5,14,40,127,408,1364,4638,16079,56401,200169,716599,2585833, %T A045632 9392704,34319666,126046498,465076159,1723092407,6407856762, %U A045632 23910255143,89493903437,335912684824,1264106399919,4768447977465,18027218146451 %N A045632 Number of 2n-bead black-white complementable necklaces with n black beads and fundamental period 2n. %H A045632 <a href="/index/Lu#Lyndon">Index entries for sequences related to Lyndon words</a> %F A045632 Moebius transform of A045629 (Christian Bower). %t A045632 A045629[n_] := If[n == 0, 1, (1/(2n)) DivisorSum[n, EulerPhi[n/#] Binomial[ 2#-1, #-1] + EulerPhi[2(n/#)] 2^(#-1)&]]; %t A045632 a[n_] := If[n == 0, 1, Sum[MoebiusMu[n/d] A045629[d], {d, Divisors[n]}]]; %t A045632 Table[a[n], {n, 0, 27}] (* _Jean-François Alcover_, Aug 28 2019 *) %K A045632 nonn %O A045632 0,4 %A A045632 _David W. Wilson_