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

1,1

Links

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

Mathematica

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

Prog

(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

Crossrefs

Intersection of A033620 and A014612.

Cf. A046401.

Sequence in context: A014612 A226527 A212582 * A376703 A066428 A228056

Adjacent sequences: A046366 A046367 A046368 * A046370 A046371 A046372

Keyword

nonn,base

Author

Patrick De Geest, Jun 15 1998

Extensions

Offset changed by Andrew Howroyd, Aug 14 2024

Name clarified by Sean A. Irvine, Jul 04 2025

Status

approved