login
A348050
Palindromes setting a new record of their number of prime divisors A001222.
0
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
1,2
MATHEMATICA
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 *)
PROG
(Python)
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
KEYWORD
nonn,base
AUTHOR
Hugo Pfoertner, Oct 25 2021
EXTENSIONS
a(1) = 1 from David A. Corneth, Oct 25 2021
a(16)-a(19) from Giorgos Kalogeropoulos, Oct 25 2021
a(20) from Michael S. Branicky, Oct 25 2021
a(21)-a(25) from Chai Wah Wu, Oct 28 2021
STATUS
approved