A331662 Odd composite numbers k such that the divisors of the binary reversal of k (A030101) are the binary reversals of the divisors of k.

9, 15, 21, 27, 45, 51, 63, 85, 93, 95, 111, 119, 123, 125, 153, 187, 189, 219, 221, 255, 335, 365, 381, 485, 511, 597, 629, 655, 681, 697, 765, 771, 831, 965, 1011, 1139, 1241, 1285, 1389, 1461, 1533, 1535, 1563, 1649, 1731, 1791, 1799, 1983, 2031, 2043, 2045

Offset: 1

Author

Amiram Eldar, Jan 23 2020

Keywords

• nonn
• base

Examples

			9 is a term since the binary representations of its divisors, 1, 3 and 9, are palindromic: 1, 11 and 1001, i.e., the binary reversals of themselves.
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, 1111101, or  1, 5, 25 and 125 in decimal representation, are the divisors of 125, which is the binary reversal of 95.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A030101.

A329419, A331663 and A331664 are subsequences.

Programs

Mathematica

Select[Range[1, 2000, 2], CompositeQ[#] && (Divisors @ IntegerReverse[#, 2]) == IntegerReverse[Divisors[#], 2] &]