A390252 Numbers k such that sigma(k) = psi(k) + omega(k)^3.

1, 4, 9, 25, 28, 49, 63, 121, 169, 175, 289, 361, 529, 841, 847, 961, 1183, 1369, 1681, 1849, 2023, 2209, 2527, 2809, 3481, 3703, 3721, 4489, 5041, 5329, 5887, 6241, 6727, 6889, 7921, 9409, 9583, 10201, 10609, 11449, 11767, 11881, 12769, 12943, 15463, 16129, 17161, 18769, 19321, 19663, 22201, 22801

Offset

1,2

Links

Table of n, a(n) for n=1..52.

Example

28 is in the sequence since sigma(28) = 56 = 48 + 2^3 = psi(28) + omega(28)^3.

Mathematica

psi[n_] := n * Times @@ (1 + 1/FactorInteger[n][[;; , 1]]); psi[1] = 1; Select[Range[23000], DivisorSigma[1, #] == psi[#] + PrimeNu[#]^3 &] (* Amiram Eldar, Oct 30 2025 *)

Crossrefs

Cf. A000203 (sigma), A001615 (psi), A001221 (omega).

Cf. A387953, A387999, A389478, A390251, A390253.

Sequence in context: A073045 A045967 A373410 * A336445 A232241 A163836

Adjacent sequences: A390249 A390250 A390251 * A390253 A390254 A390255

Keyword

nonn

Author

S. I. Dimitrov, Oct 30 2025

Status

approved