A379724 a(n) = A000668(n) - 1.

2, 6, 30, 126, 8190, 131070, 524286, 2147483646, 2305843009213693950, 618970019642690137449562110, 162259276829213363391578010288126, 170141183460469231731687303715884105726

Offset: 1

Author

Mats Granvik and Antti Karttunen, Dec 31 2024

Keywords

• nonn

Crossrefs

Cf. A000396, A000668, A023900, A072868, A379725.

Programs

Mathematica

nn = 12; A023900[n_] := DivisorSum[n, MoebiusMu[#] # &]; Table[A023900[PerfectNumber[n]], {n, 1, nn}]

Formula

a(n) = A023900(A000396(n)), provided no odd perfect numbers exist.

Conjecture; a(n) = A072868(n) - 2. - Omar E. Pol, Jan 16 2025