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 A200581 #15 Aug 02 2019 04:11:14 %S A200581 297,4456485,552604437,8291281429233,1028119449829329, %T A200581 15425912516520681549,1912814180168014341405, %U A200581 28699879385153403699122169,3558786956573202226705490361,53396068196303711362892876498613,6621116015128616782200943391318373 %N A200581 a(n) = gcd(t(n), t(2*n)), where t = A200218. %C A200581 Successive records in GCD of A200218 occurred between A200218(n) and A200218(2*n). Also, A200582 shows big increases in GCD for A200218(n) and A200218(2*n-1). %Y A200581 Cf. A200218, A200582. %K A200581 nonn %O A200581 1,1 %A A200581 _Artur Jasinski_, Nov 19 2011