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 A383142 #10 Apr 18 2025 10:59:25 %S A383142 1,2,3,5,7,11,19,29,53,87,151,267,461,811,1383,2357,4277,7499,14003, %T A383142 25931,44269,87773,152947,271563 %N A383142 Smallest positive integer with shortest addition-subtraction chain of length n. %H A383142 Neill Clift, <a href="http://additionchains.com/AdditionSubtraction.html">Addition Subtraction Chains</a>. %H A383142 <a href="/index/Com#complexity">Index to sequences related to the complexity of n</a> %F A383142 a(n) >= A003064(n). %e A383142 a(8) = 53 because 53 is the smallest positive integer k such that A128998(k) = 8. An example of a shortest addition-subtraction chain for 53 is (1 2 3 4 7 14 25 28 53). a(8) > A003064(8) because an optimal chain for A003064(8) = 47 has length 7: (1 2 3 6 12 24 23 47). %Y A383142 Cf. A003064, A128998, A383001, A383143. %K A383142 nonn,hard,more %O A383142 0,2 %A A383142 _Jinyuan Wang_, Apr 17 2025