OFFSET

0,2

COMMENTS

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.

EXAMPLE

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

CROSSREFS

KEYWORD

nonn,hard,base

AUTHOR

Chai Wah Wu, Jun 30 2020

EXTENSIONS

a(8) from David A. Corneth, Jul 01 2020

STATUS

approved