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 A265690 #6 Dec 23 2015 14:31:17 %S A265690 1,2,3,3,4,4,5,4,5,5,6,5,6,6,6,5,6,6,7,6,7,7,7,6,7,7,7,7,8,7,8,6,7,7, %T A265690 8,7,8,8,8,7,8,8,8,8,8,8,9,7,8,8,8,8,9,8,9,8,9,9,9,8,9,9,9,7,8,8,9,8, %U A265690 9,9,10,8,9,9,9,9,9,9,10,8,9,9,9,9,9,9,10,9,10,9,10,9,10,10,10,8,9,9,9,9 %N A265690 Cardinality of shortest addition chain for n. %C A265690 The cardinality of an addition chain is the number of terms in it, including the initial 1; hence it is one more than the length of the chain (A003313). %H A265690 Wikipedia, <a href="https://en.wikipedia.org/wiki/Addition_chain">Addition chain</a> %F A265690 a(n) = A003313(n) + 1. %Y A265690 Cf. A003313 (much more information and links), A265691, A265692. %K A265690 nonn %O A265690 1,2 %A A265690 _Franklin T. Adams-Watters_, Dec 13 2015