This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A331662 #9 Jan 25 2020 06:16:44 %S A331662 9,15,21,27,45,51,63,85,93,95,111,119,123,125,153,187,189,219,221,255, %T A331662 335,365,381,485,511,597,629,655,681,697,765,771,831,965,1011,1139, %U A331662 1241,1285,1389,1461,1533,1535,1563,1649,1731,1791,1799,1983,2031,2043,2045 %N 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. %H A331662 Amiram Eldar, <a href="/A331662/b331662.txt">Table of n, a(n) for n = 1..10000</a> %e A331662 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. %e A331662 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. %t A331662 Select[Range[1, 2000, 2], CompositeQ[#] && (Divisors @ IntegerReverse[#, 2]) == IntegerReverse[Divisors[#], 2] &] %Y A331662 Cf. A030101. %Y A331662 A329419, A331663 and A331664 are subsequences. %K A331662 nonn,base %O A331662 1,1 %A A331662 _Amiram Eldar_, Jan 23 2020