A366563 - OEIS

%I #10 Oct 14 2023 14:07:20

%S 1,2,2,2,2,4,2,3,3,4,2,4,2,4,4,4,2,6,2,4,4,4,2,6,3,4,4,4,2,8,2,5,4,4,

%T 4,6,2,4,4,6,2,8,2,4,6,4,2,8,3,6,4,4,2,8,4,6,4,4,2,8,2,4,6,6,4,8,2,4,

%U 4,8,2,9,2,4

%N Number of nonzero terms in row n of A366561(n,k).

%F a(n) = Sum_{k=1..n} abs(sign(A366561(n,k))).

%t nn = 74; f = x^2 - y^2; g[n_] := DivisorSum[n, MoebiusMu[#] # &]; Table[Sum[Abs[Sign[Sum[Sum[If[GCD[f, n] == k, 1, 0], {x, 1, n}], {y, 1, n}]]], {k, 1, n}], {n, 1, nn}]

%Y Cf. A366561, A366562, A000005, A320111.

%K nonn

%O 1,2

%A _Mats Granvik_, Oct 13 2023