OFFSET
1,1
LINKS
James C. McMahon, Table of n, a(n) for n = 1..1000
Mathematics Stack Exchange, Are there infinitely many "super-palindromes"?.
EXAMPLE
252 is in this list since its highest prime factor is 7. 252/7=36 is not a palindrome.
MAPLE
ispal:=proc(n) local L;
L:= convert(n, base, 10);
andmap(t -> L[-t]=L[t], [$1..nops(L)/2])
end proc:
rev:= proc(n) local L, i;
L:= convert(n, base, 10);
add(L[-i]*10^(i-1), i=1..nops(L))
end proc:
F:= proc(m)
local x1, x2, x3;
if m::even then
[seq(seq(rev(x1) + 10^(m/2)*x1, x1 = 10^(m/2-1) .. 10^(m/2)-1))]
else
[seq(seq(rev(x1) + 10^((m-1)/2)*x2 + 10^((m+1)/2)*x1, x2=0..9), x1=10^((m-1)/2-1)..10^((m-1)/2)-1)];
fi
end proc:
filter:= proc(x) not ispal(x/max(NumberTheory:-PrimeFactors(x))) end proc:
seq(op(select(filter, F(d))), d=1..4); # Robert Israel, Mar 30 2026
MATHEMATICA
q[k_]:=PalindromeQ[k]&&!PalindromeQ[k/FactorInteger[k][[-1, 1]]]; Select[Range[7000], q] (* James C. McMahon, Apr 07 2026 *)
PROG
(Python)
from itertools import islice
from sympy import primefactors
from oeis_sequences.OEISsequences import is_pal, pal10_gen
def A394546_gen(): # generator of terms
return filter(lambda m: m>1 and not is_pal(m//max(primefactors(m))), pal10_gen())
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Robin Jones, Mar 30 2026
STATUS
approved
