A046393 Palindromes with exactly 3 distinct prime factors.

66, 222, 282, 434, 474, 494, 555, 595, 606, 646, 777, 969, 1001, 1221, 1551, 1771, 2222, 2882, 3333, 3553, 4334, 4994, 5335, 5555, 5665, 5885, 5995, 6226, 6446, 6886, 7337, 7557, 7667, 7777, 7887, 8338, 8558, 8998, 9339, 9669, 9779, 9889, 11211

Offset: 1

Author

Patrick De Geest, Jun 15 1998

Keywords

• nonn
• base

Comments

The terms must have only three distinct prime factors even when counted with multiplicity. For example, 252 is not a term even though (1) it is a palindrome and (2) only three distinct primes occur when it is factored, because 252 = 2*2*3*3*7. - Harvey P. Dale, Aug 29 2016

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A046329, A046409.

Programs

Mathematica

Select[Range[12000],#==IntegerReverse[#]&&PrimeNu[#]==PrimeOmega[#]==3&] (* Harvey P. Dale, Aug 29 2016 *)