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 A253926 #25 Mar 16 2018 05:20:42 %S A253926 1,2,3,3,4,6,7,9,12,15,19,24,30,39,49,61,77,96 %N A253926 a(n) is the excess of the number of Collatz permutations of length n (with first index 15) over the n-th Fibonacci number. %C A253926 A permutation is Collatz if for some n it is the sequence of ranks of terms prior to a power of 2 generated by the Collatz function C(n) = n/2 if n even, (3n+1) if n odd. For instance, iteration of the Collatz function on 12 generates 12, 6, 3, 10, 5, which is then followed by 16, so (5,3,1,4,2) is Collatz. Among n = 1 to 14, the number of Collatz permutations is the n-th Fibonacci number; thereafter, there is an increasing excess. This sequence counts the excess. %H A253926 Michael Albert, Bjarki Gudmundsson and Henning Ulfarsson, <a href="http://arxiv.org/abs/1404.3054">Collatz meets Fibonacci</a>. arXiv:1404.3054 [math.CO], 2014-2015. Table on page 4. %Y A253926 A000045, the Fibonacci numbers, gives the number of Collatz permutations for n <= 14. %K A253926 nonn,more %O A253926 15,2 %A A253926 _William J. Keith_, Jan 19 2015