A391312 Numbers k such that sigma(k) = psi(k) + phi(k) + omega(k)^2.

24, 176, 450, 3740, 3776, 64256, 1043456, 16756736, 17545904, 148122224

Offset

1,1

Links

Table of n, a(n) for n=1..10.

Example

24 is a term since sigma(24) = 60 = 48 + 8 + 2^2 = psi(24) + phi(24) + omega(24)^2.

Prog

(PARI) isok(k) = {my(f = factor(k)); sigma(f) == prod(i=1, #f~, (f[i, 1]+1) * f[i, 1]^(f[i, 2]-1)) + eulerphi(f) + omega(f)^2; } \\ Amiram Eldar, Dec 06 2025

Crossrefs

Cf. A000203 (sigma), A001615 (psi), A000010 (phi), A001221 (omega), A390049.

Sequence in context: A209709 A375330 A209986 * A372521 A297522 A165187

Adjacent sequences: A391309 A391310 A391311 * A391313 A391314 A391315

Keyword

nonn,hard,more

Author

S. I. Dimitrov, Dec 06 2025

Extensions

a(10) from Amiram Eldar, Dec 06 2025

Status

approved