Talk:Deceptive numbers
Since the repunit ends in 1 5 can not be a factor of n--Nigel Galloway (talk) 11:44, 12 February 2022 (UTC)
Since the repunit is odd, 2 cannot be a factor of n. And because the digit sum of the repunit is n - 1, 3 cannot be a factor of n (an integer is divisible by 3, if its digit sum is divisible by 3, but n - 1 and n cannot both be divisible by 3).
All non-primes below 72 are divisible by 2, 3, or 5. So it is sufficient to start the search at 49. --Querfeld (talk) 14:01, 24 September 2023 (UTC)