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

2772, 6776, 25452, 59895, 88788, 549945, 1931391, 8117118, 8447448, 51033015, 52711725, 58344385, 103838301, 535707535, 620434026, 1663223661, 8262112628, 15271417251, 25227972252, 27747974772, 27974547972, 92628082629, 97079897079, 6421339331246, 8401825281048

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..49

Prog

(Python)
from sympy import factorint
def palQgen10(l): # generator of palindromes in base 10 of length <= 2*l
....if l > 0:
........yield 0
........for x in range(1, l+1):
............for y in range(10**(x-1), 10**x):
................s = str(y)
................yield int(s+s[-2::-1])
............for y in range(10**(x-1), 10**x):
................s = str(y)
................yield int(s+s[::-1])
A046380_list = []
for x in palQgen10(6):
....a = factorint(x)
....if sum(list(a.values())) == 6:
........for p in a:
............s = str(p)
............if s != s[::-1]:
................break
........else:
............A046380_list.append(x) # Chai Wah Wu, Dec 26 2014

Crossrefs

Cf. A046332.

Sequence in context: A205418 A231709 A046332 * A249228 A154081 A362876

Adjacent sequences: A046377 A046378 A046379 * A046381 A046382 A046383

Keyword

nonn,base

Author

Patrick De Geest, Jun 15 1998

Extensions

a(19)-a(25) from Chai Wah Wu, Dec 26 2014

Status

approved