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a(n) is the denominator of the median abundancy index of the first 2^n + 1 positive integers.
2

%I #5 Apr 30 2022 10:35:35

%S 3,3,9,2,21,29,41,59,73,107,139,157,4941,7707,157,1929,1973,7643,

%T 147749,313733,1774479,1015973,1615943,6646647,3280781,5670497,

%U 31673271,21228137

%N a(n) is the denominator of the median abundancy index of the first 2^n + 1 positive integers.

%C See A353615 for more details.

%t With[{m = 20}, t = Table[DivisorSigma[-1, n], {n, 1, 2^m + 1}]; Denominator @ Table[Median[t[[1 ;; 2^n + 1]]], {n, 1, m}]]

%Y Cf. A000203, A017665, A017666, A353615 (numerators), A353617.

%K nonn,frac,more

%O 1,1

%A _Amiram Eldar_, Apr 30 2022