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 A050411 #18 Aug 17 2021 02:39:55 %S A050411 4,1,7,9,2,12,3,15,17,4,20,22,5,25,6,28,30,7,33,8,36,38,9,41,43,10,46, %T A050411 11,49,51,12,54,56,13,59,14,62,64,15,67,16,70,72,17,75,77,18,80,19,83, %U A050411 85,20,88,21,91,93,22,96,98,23,101,24,104,106,25,109,111,26,114,27,117,119,28,122,29,125 %N A050411 Analog of 3x+1 function. %C A050411 Iterates diverge for all n except n>2 in A005248. %H A050411 K. S. Stolarsky, <a href="https://doi.org/10.1080/10236199808808155">A prelude to the 3x+1 problem</a>, J. Differ. Equations Appl. 4 (1998), no. 5, 451-461. %F A050411 f([phi n]) = [phi^2 n]+2; f([phi^2 n]) = n. phi = (1+sqrt(5))/2. %F A050411 a(n) = ceiling(ceiling(n/phi) * phi^2) + 1 if n is in A000201, otherwise a(n) = ceiling(n/phi^2) = A189663(n+1). - _Sean A. Irvine_, Aug 15 2021 %Y A050411 Cf. A000201, A001950, A005248, A189663. %K A050411 nonn %O A050411 1,1 %A A050411 _David W. Wilson_