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A355790
Numbers that can be written as the product of two divisors greater than 1 such that the number is contained in the string concatenation of the divisors.
4
64, 95, 110, 210, 325, 510, 624, 640, 664, 950, 995, 1010, 1100, 1110, 3250, 3325, 5134, 6240, 6400, 6640, 6664, 7125, 7616, 8145, 9500, 9950, 9995, 11000, 11100, 11110, 20100, 21052, 21175, 25100, 26208, 32500, 33250, 33325, 35126, 50100, 51020, 51204, 51340, 57125, 62400, 64000, 65114
OFFSET
1,1
LINKS
Scott R. Shannon, Divisor product of the first 232 terms. These are all the numbers up to 50000000.
EXAMPLE
64 is a term as 64 = 16 * 4 and "16" + "4" = "164" contains "64".
65114 is a term as 65114 = 4651 * 14 and "4651" + "14" = "465114" contains "65114".
See the attached text file for other examples.
PROG
(Python)
from sympy import divisors
def ok(n):
s, divs = str(n), divisors(n)[1:-1]
return any(s in str(d)+str(n//d) for d in divs)
print([k for k in range(1, 10**5) if ok(k)]) # Michael S. Branicky, Jul 27 2022
KEYWORD
nonn,base
AUTHOR
Scott R. Shannon, Jul 17 2022
STATUS
approved