Six of the factors of 1221 are palindromes: {1,3,11,33,111,1221} but two are not: {37,407}
(A) What number under one million has the most palindrome factors?
Some numbers have only palindromes as factors. Examples include 88: {1,2,4,8,11,22,44,88} and any palindromic prime
(B) Find the smallest number with at least as many palindrome factors as part (A) but having only palindrome factors.
(In reply to
re: My thoughts on the difficulty of part (B) by Charlie)
Right you are. Though there don't have to be exactly three 1's in it. The point is if there are enough zeros between the ones, the product will be a new palindrome. (There are other limits on the number of 1's)
Is this prime for some numbers of zeros? a,b,b,a
10...010...010...010...01
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Posted by Jer
on 2022-03-16 08:56:21 |
re(2): My thoughts on the difficulty of part (B)
