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%I #16 Aug 21 2019 21:45:41
%S 1,2,10,78,777,9800,149796,2690420,55555500,1296871224,33773107758,
%T 970753545580,30527491279005,1042604500906800,38430716820193144,
%U 1520662246114589640,64291516462902839175,2892426397164199846860,137970526315789473684210,6955460736173788715925048,369510689788116404049535299
%N Main diagonal of array in A098691.
%C a(n) is the number of self-complementary n-bead primitive necklaces of n+1 colors (see Miller (1978)). - _Petros Hadjicostas_, Aug 21 2019
%H Alois P. Heinz, <a href="/A098692/b098692.txt">Table of n, a(n) for n = 1..387</a>
%H H. Meyn and W. Götz, <a href="http://www.mat.univie.ac.at/~slc/opapers/s21meyn.html">Self-reciprocal polynomials over finite fields</a>, Séminaire Lotharingien de Combinatoire, B21d (1989), 8 pp.
%H R. L. Miller, <a href="http://dx.doi.org/10.1016/0012-365X(78)90043-2">Necklaces, symmetries and self-reciprocal polynomials</a>, Discr. Math. 22 (1978), 25-33.
%F a(n) = ((n + 1)^n - 1)/(2*n) if n = 2^s (for s >= 1), and (1/(2*n)) * Sum_{d|n, d odd} mu(d) * (n + 1)^(n/d) otherwise. - _Petros Hadjicostas_, Aug 21 2019
%p with(numtheory):
%p a:= n-> `if`(n=2^ilog2(n) and n>1, (n+1)^n-1, add(mobius(d)*
%p (n+1)^(n/d), d=select(x-> x::odd, divisors(n))))/(2*n):
%p seq(a(n), n=1..20); # _Alois P. Heinz_, Aug 21 2019
%Y Cf. A098691.
%K nonn
%O 1,2
%A _Ralf Stephan_, Sep 21 2004
%E More terms by _Petros Hadjicostas_, Aug 21 2019
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