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A046380 Palindromes with exactly 6 palindromic prime factors (counted with multiplicity).

%I A046380 #16 May 22 2025 10:20:06
%S A046380 2772,6776,25452,59895,88788,549945,1931391,8117118,8447448,51033015,
%T A046380 52711725,58344385,103838301,535707535,620434026,1663223661,
%U A046380 8262112628,15271417251,25227972252,27747974772,27974547972,92628082629,97079897079,6421339331246,8401825281048
%N A046380 Palindromes with exactly 6 palindromic prime factors (counted with multiplicity).
%H A046380 Chai Wah Wu, <a href="/A046380/b046380.txt">Table of n, a(n) for n = 1..49</a>
%o A046380 (Python)
%o A046380 from sympy import factorint
%o A046380 def palQgen10(l): # generator of palindromes in base 10 of length <= 2*l
%o A046380     if l > 0:
%o A046380         yield 0
%o A046380         for x in range(1,l+1):
%o A046380             for y in range(10**(x-1),10**x):
%o A046380                 s = str(y)
%o A046380                 yield int(s+s[-2::-1])
%o A046380             for y in range(10**(x-1),10**x):
%o A046380                 s = str(y)
%o A046380                 yield int(s+s[::-1])
%o A046380 A046380_list = []
%o A046380 for x in palQgen10(6):
%o A046380     a = factorint(x)
%o A046380     if sum(list(a.values())) == 6:
%o A046380         for p in a:
%o A046380             s = str(p)
%o A046380             if s != s[::-1]:
%o A046380                 break
%o A046380         else:
%o A046380             A046380_list.append(x) # _Chai Wah Wu_, Dec 26 2014
%Y A046380 Cf. A046332.
%K A046380 nonn,base
%O A046380 1,1
%A A046380 _Patrick De Geest_, Jun 15 1998
%E A046380 a(19)-a(25) from _Chai Wah Wu_, Dec 26 2014