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 A163949 #6 Aug 17 2017 06:01:08 %S A163949 0,3,15,138,1720,27180,522984 %N A163949 The number of functions in a finite set that are not obtainable by a composition power of any other function. Similar to A163947, but it excludes self compositions. %C A163949 It is similar to A163947, but the difference is expressed by the nontrivial sequence: 0, 3, 9, 54, 320, 1590, 6552... excluding solutions by powers of the function itself. %F A163949 a(n) = n^n - A163950(n). %Y A163949 Cf. A163947, A163950. %K A163949 more,nonn %O A163949 1,2 %A A163949 _Carlos Alves_, Aug 06 2009