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 A335883 #15 Jul 08 2020 10:21:17 %S A335883 1,3,5,11,23,47,109,229,457,1033,2161,4703,10079,20663,43223,94033, %T A335883 208849,420457,872687,1849921,3699841,8748001,17496001,36998411 %N A335883 The least k for which A335884(k) = n. %C A335883 Because A335884 is fully additive and a(1) = 3, we have a(n) <= 3^n and in particular, a(n+1) <= 3*a(n), n > 0 and more generally a(n + m) <= a(n) * a(m) where m, n >= 0. (See also comments in A334099.) %C A335883 a(16) = 208849 = 457^2 = a(8)*a(8) is the first composite term. %F A335883 For all n >= 0, A335884(a(n)) = n. %Y A335883 Cf. A335884. %K A335883 nonn,more %O A335883 0,2 %A A335883 _Antti Karttunen_, Jun 29 2020 %E A335883 a(21)-a(23) from _Jinyuan Wang_, Jul 08 2020