A046395 Palindromes that are the product of 5 distinct primes.

6006, 8778, 20202, 28182, 41514, 43134, 50505, 68586, 87978, 111111, 141141, 168861, 202202, 204402, 209902, 246642, 249942, 262262, 266662, 303303, 323323, 393393, 399993, 438834, 454454, 505505, 507705, 515515, 516615, 519915, 534435, 535535, 543345

Offset: 1

Author

Patrick De Geest, Jun 15 1998

Keywords

• nonn
• base

Comments

No exponent of the distinct prime factors can be greater than one, i.e., no prime powers are permitted. - Harvey P. Dale, Apr 09 2021 at the suggestion of Sean A. Irvine

See A373465 for the similar sequence where only distinct prime divisors are counted, but may occur to higher powers. - M. F. Hasler, Jun 06 2024

Examples

			505505 = 5 * 7 * 11 * 13 * 101.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..500

Crossrefs

Cf. A002113 (palindromes), A051270 (omega(.) = 5).

Cf. A046331 (palindromes with 5 prime factors counted with multiplicity), A373465 (counting only distinct prime divisors).

Programs

Mathematica

Select[Range[550000],PalindromeQ[#]&&PrimeNu[#]==PrimeOmega[#]==5&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Apr 09 2021 *)

Formula

Intersection of A002113 and A046387.

Extensions

Corrected at the suggestion of Sean A. Irvine by Harvey P. Dale, Apr 09 2021

Name edited to avoid confusion by M. F. Hasler, Jun 06 2024