A371075 Fixed points of A374941.

12, 30, 80, 324, 448, 888, 11264, 53248, 1114112, 3684352, 4980736, 18055168, 96468992

Offset: 1

Author

Tanmaya Mohanty, Mar 10 2024

Keywords

• nonn
• more

Examples

			12 is a term because A374941(12) = 12.
		

Crossrefs

Cf. A000396, A005101, A299795, A374941.

Programs

PARI

f(n) = my(d=divisors(n)); sum(i=2, #d-1, if (isprime(d[i]), d[i], f(d[i])));
isok(k) = f(k) == k; \\ Michel Marcus, Mar 10 2024

Python

from sympy import divisors, isprime
from functools import cache
@cache
def f(n): return sum(di if isprime(di) else f(di) for di in divisors(n)[1:-1])
def ok(n): return n == f(n)
print([k for k in range(1, 1000) if ok(k)]) # Michael S. Branicky, Mar 31 2024 after Michel Marcus

Formula

Equals the ordered set {k: A374941(k) = k}.

Extensions

a(13) from Michael S. Branicky, Mar 31 2024