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a(n) = A006571(A005117(n)).
0

%I #54 Oct 14 2023 14:05:02

%S 1,-2,-1,1,2,-2,-2,1,4,4,-1,-2,0,2,-2,-1,-8,0,2,7,-1,4,-2,3,0,-4,-8,

%T -4,-6,2,8,2,-6,1,0,0,5,12,-14,4,2,-7,1,4,-3,4,-6,-2,8,-10,16,-6,-2,

%U 12,0,15,-8,-7,-16,0,-7,2,-4,-16,2,12,18,10,-2,-3,9,0,-1

%N a(n) = A006571(A005117(n)).

%F a(n) = A006571(A005117(n)).

%F Conjecture: a(n) = A366450(A005117(n)), verified up to n = 98.

%t nn = 73; squareFree = Select[Range[8*nn], SquareFreeQ]; b[n_] := SeriesCoefficient[q (Product[(1 - q^k), {k, 11, n, 11}] Product[1 - q^k, {k, n}])^2, {q, 0, n}]; Table[b[squareFree[[n]]], {n, 1, nn}]

%Y Cf. A006571, A366450, A005117, A002070, A023900, A191898, A366362.

%K sign

%O 1,2

%A _Mats Granvik_, Oct 10 2023