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 A178909 #26 Oct 28 2019 16:19:19 %S A178909 1,6,36,54,120,2470,2640,3144,3780,32640,41280,52632,67184,1098176, %T A178909 1157904,2147450880 %N A178909 Indices of perfect polynomials over GF(2). %C A178909 Numbers k such that k = A178908(k); sum of divisors of k-th GF(2) polynomial is the polynomial itself. %C A178909 a(17) > 5*10^9. - _Amiram Eldar_, Oct 28 2019 %o A178909 (PARI) isok(n) = my(s = vecsum(divisors(Mod(1,2)*Pol(binary(n))))); subst(lift(s), x, 2) == n; \\ _Michel Marcus_, Jan 13 2019 %Y A178909 Cf. A178908, A091220, A000396, A178911. %K A178909 nonn,more %O A178909 1,2 %A A178909 _Franklin T. Adams-Watters_, Jun 22 2010 %E A178909 a(14)-a(15) from _Amiram Eldar_, Jan 13 2019 %E A178909 a(16) from _Amiram Eldar_, Oct 28 2019