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 A331587 #12 Jan 22 2020 12:57:04 %S A331587 1,9,25,49,81,143,225,289,441,475,667,729,961,1089,1517,1715,2025, %T A331587 2223,2279,2601,2867,3245,3969,4225,5329,5589,6499,6853,7225,7875, %U A331587 8023,8383,8649,9559,9801,9919,10179,11449,11845,11875,13653,14161,16129,16641,19865 %N A331587 Odd numbers of the form k * reverse(k) (where reverse(k) is the binary reversal of k, A030101(k)). %C A331587 A192775 is a subsequence. %H A331587 Rémy Sigrist, <a href="/A331587/b331587.txt">Table of n, a(n) for n = 1..8347</a> %e A331587 The binary representations of 11 and of 13 are "1011" and "1101", respectively, so 11*13 = 143 belongs to the sequence. %o A331587 (PARI) is(n) = if (n%2, fordiv (n, d, if (d*fromdigits(Vecrev(binary(d)),2)==n, return (1)))); return (0) %Y A331587 Cf. A030101, A092213, A192775, A331588, A331589. %K A331587 nonn,base %O A331587 1,2 %A A331587 _Rémy Sigrist_, Jan 21 2020