A037920 Trajectory of 8 under prime factor concatenation procedure.

8, 2, 2, 2, 2, 3, 37, 3, 19, 41, 3, 3, 3, 7, 13, 13, 3, 11123771, 7, 149, 317, 941, 229, 31219729, 11, 2084656339, 3, 347, 911, 118189, 11, 613, 496501723, 97, 130517, 917327, 53, 1832651281459, 3, 3, 3, 11, 139, 653, 3863, 5107

Offset: 0

Author

Jeff Burch

Keywords

• fini
• full
• nonn
• tabf
• base

Links

• Patrick De Geest, Home Primes

Crossrefs

Cf. A037273, A006919.

Programs

Python

from sympy import factorint
def iterate(n):
    flst, f = [n], sorted(factorint(n, multiple=True))
    while len(f) > 1:
        flst += f
        f = sorted(factorint(int("".join(map(str, f))), multiple=True))
    return flst
print(iterate(8)) # Michael S. Branicky, Aug 02 2021

Extensions

Edited by Charles R Greathouse IV, Apr 30 2010