A358068 Numbers that share a (decimal) digit with the sum of their proper divisors.

6, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 26, 28, 31, 32, 35, 40, 41, 42, 44, 46, 51, 56, 60, 61, 64, 68, 70, 71, 72, 74, 76, 80, 84, 86, 91, 93, 95, 96, 100, 101, 102, 103, 104, 106, 107, 108, 109, 110, 111, 112, 113, 114, 120, 121, 124, 125, 126, 127, 128, 130, 131, 132, 135, 136

Offset

1,1

Links

Table of n, a(n) for n=1..65.

Wikipedia, Table of divisors

Example

72 is in the sequence since 72 shares a digit with the sum of its proper divisors 123. Both numbers share the digit "2".

Prog

(Python)
from itertools import count, islice
from sympy import divisor_sigma
def A358068_gen(startvalue=2): # generator of terms >= startvalue
    for n in count(max(startvalue, 2)):
        s = set(str(divisor_sigma(n)-n))
        if any(d in s for d in set(str(n))):
            yield n
A358068_list = list(islice(A358068_gen(), 30)) # Chai Wah Wu, Oct 29 2022
(PARI) isok(n) = #setintersect(Set(digits(sigma(n)-n)), Set(digits(n))); \\ Michel Marcus, Oct 30 2022

Crossrefs

Cf. A001065, A357929.

Sequence in context: A103704 A135998 A242825 * A276136 A152089 A212773

Adjacent sequences: A358065 A358066 A358067 * A358069 A358070 A358071

Keyword

nonn,base

Author

Wesley Ivan Hurt, Oct 29 2022

Status

approved