login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Smallest palindrome in base 10 whose factorization contains n distinct base 10 palindromic prime factors.
0

%I #10 Jul 01 2020 20:32:27

%S 1,2,6,66,2772,279972,67566576,5159488849515,83797355379738

%N Smallest palindrome in base 10 whose factorization contains n distinct base 10 palindromic prime factors.

%C For n <= 6, a(n) does not have a non-palindromic prime factor, i.e. a(n) has n distinct prime factors and they are all palindromes. On the other hand, a(7) contains a prime factor 13, which is not a palindrome.

%e a(6) = 67566576 = 2^4*3*7*11*101*181 has 6 distinct palindromic prime factors.

%Y Cf. A002113, A002385, A046385, A309565.

%K nonn,hard,base

%O 0,2

%A _Chai Wah Wu_, Jun 30 2020

%E a(8) from _David A. Corneth_, Jul 01 2020