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 A083800 #6 Nov 04 2015 12:39:01 %S A083800 0,1,5,13,23,47,59,59,839,1679,2519,15119,27719,138599,360359,360359, %T A083800 720719,8648639,12252239,208288079,232792559,232792559,232792559, %U A083800 2327925599,5354228879,16062686639,26771144399,26771144399,80313433199,1204701497999,2329089562799,16303626939599,144403552893599 %N A083800 First column of A083798. %Y A083800 Cf. A083796, A083797, A083798, A083799, A083801, A083802. %K A083800 nonn %O A083800 1,3 %A A083800 _Amarnath Murthy_ and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003 %E A083800 Corrected and extended by _Max Alekseyev_, Nov 04 2015