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 A077600 #12 Sep 13 2012 10:04:54
%S A077600 0,1,2,3,2,3,2,5,4,3,2,5,4,3,4,5,4,5,2,5,4,3,2,7,6,5,6,5,4,5,4,7,4,5,
%T A077600 4,7,6,5,6,7,4,5,4,5,6,5,4,7,6,7,6,5,4,7,4,5,4,5,4,7,6,5,8,7,6,5,6,9,
%U A077600 6,5,4,9,8,5,8,9,4,5,4,7,8,7,4,7,6,7,6,7,4,9,4,7,8,5,6,7,6,9,8
%N A077600 Number of real roots for the n-th Moebius polynomial, M(n,x), which satisfies M(n,-1)=mu(n) the Moebius function of n.
%t A077600 m[1, x_] = 1; m[n_, x_] := m[n, x] = 1 + Sum[x*m[k, x]*Floor[n/k], {k, 1, n-1}] // Expand; a[n_] := CountRoots[m[n, x], x]; Table[a[n], {n, 1, 99}] (* _Jean-François Alcover_, Sep 13 2012 *)
%Y A077600 Cf. A074586, A074587, A077596, A077597, A077598, A077599, A077601.
%K A077600 nonn
%O A077600 1,3
%A A077600 _Benoit Cloitre_ and _Paul D. Hanna_, Nov 10 2002
%E A077600 Typo (?) a(45)=4 replaced with 6 by _Jean-François Alcover_, Sep 13 2012