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URL: https://oeis.org/A331663

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A331663
Odd composite numbers k with at least one divisor that is not a binary palindrome (A006995) such that the divisors of the binary reversal of k (A030101) are the binary reversals of the divisors of k.
3
95, 111, 123, 125, 187, 221, 335, 485, 597, 629, 655, 681, 697, 831, 965, 1011, 1139, 1389, 1461, 1535, 1563, 1649, 1731, 1791, 1983, 2031, 2043, 2045, 2227, 2493, 2605, 2733, 2827, 2885, 2901, 3033, 3099, 3279, 3281, 3327, 3341, 3459, 3647, 3891, 4039, 4083
OFFSET
1,1
LINKS
EXAMPLE
95 is a term since the binary representations of its divisors, 1, 5, 19, and 95, are 1, 101, 10011 and 1011111, and their binary reversals, 1, 101, 11001 and 1111101, or 1, 5, 25 and 125 in decimal representation, are the divisors of 125, which is the binary reversal of 95, and 19 and 95 are not binary palindromes.
MATHEMATICA
binPalQ[n_] := PalindromeQ @ IntegerDigits[n, 2]; Select[Range[1, 4000, 2], CompositeQ[#] && (Divisors @ IntegerReverse[#, 2]) == IntegerReverse[(d = Divisors[#]), 2] && !AllTrue[Rest[d], binPalQ] &]
CROSSREFS
Complement of A329419 with respect to A331662.
A331664 is a subsequence.
Sequence in context: A338581 A306303 A181767 * A046005 A339522 A045121
KEYWORD
nonn,base
AUTHOR
Amiram Eldar, Jan 23 2020
STATUS
approved