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 A331664 #10 Jan 25 2020 09:08:02 %S A331664 4847,5371,7141,7913,22891,23243,27053,27469,47863,48599,60349,61277, %T A331664 69211,73343,77251,80623,81863,89339,100201,111841,114293,116729, %U A331664 126649,130289,138623,180163,200693,260833,286141,319381,348121,371899,383339,388561,439517,453037 %N A331664 Odd composite numbers k all of whose divisors larger than 1 are not binary palindromes (A006995) such that the divisors of the binary reversal of k (A030101) are the binary reversals of the divisors of k. %H A331664 Amiram Eldar, <a href="/A331664/b331664.txt">Table of n, a(n) for n = 1..2000</a> %e A331664 4847 is a term since the binary representations of its divisors, 1, 37, 131 and 4847, are 1, 100101, 10000011 and 1001011101111, and their binary reversals, 1, 101001, 11000001 and 1111011101001, or 1, 41, 193 and 7913 in decimal representation, are the divisors of 7913, and none of the divisors of 4847 except 1 are binary palindromes. %t A331664 binPalQ[n_] := PalindromeQ @ IntegerDigits[n, 2]; Select[Range[1, 5*10^5, 2], CompositeQ[#] && (Divisors@IntegerReverse[#, 2]) == IntegerReverse[(d = Divisors[#]), 2] && !AnyTrue[Rest[d], binPalQ] &] %Y A331664 Cf. A006995, A030101, A329419. %Y A331664 Subsequence of A331662 and A331663. %K A331664 nonn,base %O A331664 1,1 %A A331664 _Amiram Eldar_, Jan 23 2020