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

1,1

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

Links

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

Formula

Intersection of A002113 and A046387.

Example

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

Mathematica

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

Crossrefs

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

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

Sequence in context: A343432 A115429 A373465 * A143043 A031605 A239176

Adjacent sequences: A046392 A046393 A046394 * A046396 A046397 A046398

Keyword

nonn,base

Author

Patrick De Geest, Jun 15 1998

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

Status

approved