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 A191534 #15 May 13 2013 01:49:38 %S A191534 11,155,2164,33723,539379,8396540,136109403,2147745531,34360623100, %T A191534 549771505659,8797030442667,140737513521148,2251823188540923, %U A191534 36028801313906427,576460760876579772 %N A191534 Least k with 2n divisors such that k-1 and k+1 in binary representation have same number 2n of 0's as 1's. %C A191534 Does a(n) exist for every n? It seems plausible at first glance; asymptotically there should be enough numbers in the range 16^n * [1/2, 1] that have 2n divisors (since 16 > e). [_Charles R Greathouse IV_, Jun 05 2011] %C A191534 a(16) <= 9223372071079772155. - _Donovan Johnson_, Sep 25 2011 %o A191534 (PARI) a(n)=my(v=vector(4*n,i,i>2*n));for(k=1<<(4*n-1)+1<<(2*n-1)-1,1<<(4*n)-1<<(2*n),if(vecsort(binary(k-1))==v & vecsort(binary(k+1))==v & numdiv(k)==2*n, return(k))) \\ _Charles R Greathouse IV_, Jun 05 2011 %Y A191534 Cf. A000005, A191292, A191369. %K A191534 nonn,base %O A191534 1,1 %A A191534 _Juri-Stepan Gerasimov_, Jun 05 2011 %E A191534 a(5)-a(11) from _Charles R Greathouse IV_, Jun 05 2011 %E A191534 a(12)-a(15) from _Donovan Johnson_, Sep 25 2011