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