A391908 Numbers k such that sigma(k) = psi(k) + phi(k) + omega(k)^5.

1984, 2760, 24852, 36084, 49044, 57088, 245248, 377910, 1014784, 11507958, 16350500, 151632054, 170747262, 246570534, 463572774, 1011059264, 2035069974, 7980282656

Offset

1,1

Links

Table of n, a(n) for n=1..18.

Example

1984 is a term since sigma(1984) = 4064 = 3072 + 960 + 2^5 = psi(1984) + phi(1984) + omega(1984)^5.

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)^5; } \\ Amiram Eldar, Dec 23 2025

Crossrefs

Cf. A000203 (sigma), A001615 (psi), A000010 (phi), A001221 (omega), A390049, A391312, A391749, A391763.

Sequence in context: A252693 A166876 A028238 * A022063 A107527 A034228

Adjacent sequences: A391905 A391906 A391907 * A391909 A391910 A391911

Keyword

nonn,hard,more

Author

S. I. Dimitrov, Dec 23 2025

Extensions

a(12)-a(18) from Amiram Eldar, Dec 23 2025

Status

approved