A046369 Numbers with exactly 3 prime factors (counted with multiplicity), all of which are palindromes.

8, 12, 18, 20, 27, 28, 30, 42, 44, 45, 50, 63, 66, 70, 75, 98, 99, 105, 110, 125, 147, 154, 165, 175, 231, 242, 245, 275, 343, 363, 385, 404, 524, 539, 604, 605, 606, 724, 764, 786, 847, 906, 909, 1010, 1086, 1146, 1179, 1252, 1310, 1331, 1359, 1412, 1414

Offset: 1

Author

Patrick De Geest, Jun 15 1998

Keywords

• nonn
• base

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..1000

Crossrefs

Intersection of A033620 and A014612.

Cf. A046401.

Programs

Mathematica

Select[Range[1500],PrimeOmega[#]==3&&AllTrue[FactorInteger[#][[;;,1]],PalindromeQ]&] (* Harvey P. Dale, Jul 04 2025 *)

Python

from sympy import factorint
def pal(n): s = str(n); return s == s[::-1]
def ok(n):
    f = factorint(n)
    return sum(f.values())==3 and all(pal(p) for p in f)
print([k for k in range(1415) if ok(k)]) # Michael S. Branicky, Jul 04 2025

Extensions

Offset changed by Andrew Howroyd, Aug 14 2024

Name clarified by Sean A. Irvine, Jul 04 2025