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 A045632 Number of 2n-bead black-white complementable necklaces with n black beads and fundamental period 2n. 1
 1, 1, 1, 2, 5, 14, 40, 127, 408, 1364, 4638, 16079, 56401, 200169, 716599, 2585833, 9392704, 34319666, 126046498, 465076159, 1723092407, 6407856762, 23910255143, 89493903437, 335912684824, 1264106399919, 4768447977465, 18027218146451 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS FORMULA Moebius transform of A045629 (Christian Bower). MATHEMATICA A045629[n_] := If[n == 0, 1, (1/(2n)) DivisorSum[n, EulerPhi[n/#] Binomial[ 2#-1, #-1] + EulerPhi[2(n/#)] 2^(#-1)&]]; a[n_] := If[n == 0, 1, Sum[MoebiusMu[n/d] A045629[d], {d, Divisors[n]}]]; Table[a[n], {n, 0, 27}] (* Jean-François Alcover, Aug 28 2019 *) CROSSREFS Sequence in context: A301871 A076866 A151417 * A148321 A007463 A159308 Adjacent sequences:  A045629 A045630 A045631 * A045633 A045634 A045635 KEYWORD nonn AUTHOR STATUS approved

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Last modified December 12 09:36 EST 2019. Contains 329953 sequences. (Running on oeis4.)