A046382
Palindromes with exactly 8 prime factors (counted with multiplicity) each of which is a palindrome.
Original entry on oeis.org
2112, 25152, 67776, 2171712, 2190912, 2384832, 2559552, 6142416, 26011062, 213909312, 215080512, 215656512, 217787712, 232727232, 234474432, 251737152, 255999552, 270939072, 291888192, 616535616, 616727616, 618666816, 618858816, 635545536, 637676736, 652808256
Offset: 1
The palindrome 217787712 is a term since it has 8 factors 2^6 3 1134311, all palindromic.
A046398
Palindromes with exactly 8 distinct prime factors.
Original entry on oeis.org
244868442, 1346776431, 2012112102, 2050550502, 2222442222, 2274994722, 2402442042, 2435775342, 2601661062, 2615775162, 2806886082, 4116996114, 4163773614, 4188998814, 4305335034, 4501551054, 4515665154, 4542992454
Offset: 1
A348050
Palindromes setting a new record of their number of prime divisors A001222.
Original entry on oeis.org
1, 2, 4, 8, 88, 252, 2112, 4224, 8448, 44544, 48384, 405504, 4091904, 405909504, 677707776, 4285005824, 21128282112, 29142024192, 4815463645184, 445488555884544, 27874867776847872, 40539458585493504, 63556806860865536, 840261068860162048, 4870324782874230784
Offset: 1
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m=0;lst=Union@Flatten[Table[{FromDigits@Join[s=IntegerDigits@n,Reverse@s],FromDigits@Join[w=IntegerDigits@n,Rest@Reverse@w]},{n,10^5}]];Do[t=PrimeOmega@lst[[n]];If[t>m,Print@lst[[n]];m=t],{n,Length@lst}] (* Giorgos Kalogeropoulos, Oct 25 2021 *)
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from sympy import factorint
from itertools import product
def palsthru(maxdigits):
midrange = [[""], [str(i) for i in range(10)]]
for digits in range(1, maxdigits+1):
for p in product("0123456789", repeat=digits//2):
left = "".join(p)
if len(left) and left[0] == '0': continue
for middle in midrange[digits%2]:
yield int(left+middle+left[::-1])
def afind(maxdigits):
record = -1
for p in palsthru(maxdigits):
f = factorint(p, multiple=True)
if p > 0 and len(f) > record:
record = len(f)
print(p, end=", ")
afind(10) # Michael S. Branicky, Oct 25 2021
Showing 1-3 of 3 results.