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URL: https://oeis.org/A386637

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A386637
Numbers k such that sigma(k) = psi(k) + tau(k) + omega(k).
9
28, 63, 175, 847, 1183, 2023, 2527, 3703, 5887, 6727, 9583, 11767, 12943, 15463, 19663, 24367, 26047, 31423, 35287, 37303, 43687, 48223, 55447, 65863, 71407, 74263, 80143, 83167, 89383, 112903, 120127, 131383, 135247, 155407, 159607, 172543, 185983, 195223, 209503, 224287, 229327
OFFSET
1,1
EXAMPLE
28 is in the sequence since sigma(28) = 56 = 48 + 6 + 2 = psi(28) + tau(28) + omega(28).
MATHEMATICA
psi[n_] := n*Times @@ (1 + 1/FactorInteger[n][[;; , 1]]); psi[1] = 1; Select[Range[230000], DivisorSigma[1, #] == psi[#] + DivisorSigma[0, #] + PrimeNu[#] &] (* Amiram Eldar, Oct 23 2025 *)
CROSSREFS
Cf. A000203 (sigma), A001615 (psi), A000005 (tau), A001221 (omega).
Sequence in context: A159652 A038641 A342756 * A043386 A044130 A044511
KEYWORD
nonn
AUTHOR
S. I. Dimitrov, Oct 22 2025
STATUS
approved