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A389856

Numbers k such that sigma(k) = phi(k) + tau(k) + pi(k).

4, 9, 11611, 35891, 36119, 6174967, 15716783, 1733187301

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..8.

EXAMPLE

11611 is in the sequence since sigma(11611) = 12312 = 10912 + 4 + 1396 = phi(11611) + tau(11611) + pi(11611).

PROG

(PARI) list(lim) = {my(q = 2, m = 0, f); forprime(p = 3, lim, m++; for(k = q, p-1, f = factor(k); if(sigma(f) == eulerphi(f) + numdiv(f) + m, print1(k, ", "))); q = p); } \\ Amiram Eldar, Oct 17 2025

CROSSREFS

Cf. A000005, A000010, A000203, A000720, A067788, A388001, A389855.

Sequence in context: A260305 A229338 A392805 * A111443 A299118 A331450

Adjacent sequences: A389853 A389854 A389855 * A389857 A389858 A389859

KEYWORD

nonn,hard,more

AUTHOR

S. I. Dimitrov, Oct 17 2025

EXTENSIONS

a(6)-a(8) from Amiram Eldar, Oct 17 2025

STATUS

approved

URL: https://oeis.org/A389856

⇱ A389856 - OEIS