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 A085649 #12 Sep 18 2024 14:58:19
%S A085649 4,10,533,671,869,1139,2279,14873,17819,20651,22523,23129,23381,25199,
%T A085649 28013,28943,31439,31571,33899,35369,35621,37241,37403,39059,39449,
%U A085649 41291,42401,42431,42881,43259,45173,45803,49583,49649,49949,50621
%N A085649 Brilliant numbers k such that 2k+1 is also brilliant.
%e A085649 1139 is a member because 1139 = 17*67 and 1139*2+1 = 2279 = 43*53.
%o A085649 (PARI) isA078972(k)={my(f=factor(k));bigomega(f)==2 && (f[1,2]==2 || logint(f[1,1],10)==logint(f[2,1],10))}
%o A085649 isok(k)={isA078972(k) && isA078972(2*k+1)} \\ _Andrew Howroyd_, Sep 18 2024
%Y A085649 Subsequence of A111153.
%Y A085649 Cf. A078972.
%K A085649 base,nonn
%O A085649 1,1
%A A085649 _Jason Earls_, _Amarnath Murthy_, Jul 11 2003
%E A085649 Offset changed by _Andrew Howroyd_, Sep 18 2024