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 A230528 #42 Feb 09 2024 15:33:39 %S A230528 375494703,602641031,619418303,728117339,750793519,750832687,750989359 %N A230528 Numbers k such that a shortest addition chain for 2*k is shorter than one for k, that is, A003313(2*k) < A003313(k). %C A230528 Can the shortest addition chain for 2*k be shorter than one for k by more than 1? - _Alexey Slizkov_, Jan 20 2024 %H A230528 Neill Michael Clift, <a href="http://dx.doi.org/10.1007/s00607-010-0118-8">Calculating optimal addition chains</a>, Computing 91.3 (2011): 265-284. %H A230528 V. Zhuravlev and P. Samovol, <a href="http://kvant.mccme.ru/pdf/2013/2013-02.pdf">Faster than the fastest, or can one beat the binary algorithm</a>, Kvant 2 (2013), 7-15. (in Russian) %Y A230528 Cf. A003313, A086878, A115016, A256653. %K A230528 nonn,hard,more,nice %O A230528 1,1 %A A230528 _Max Alekseyev_, Oct 22 2013 %E A230528 a(1) = 375494703 was found by _Neill M. Clift_ (2011) %E A230528 a(2)-a(7) from _Hugo Pfoertner_, Dec 19 2015