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 A204540 #35 Jun 13 2025 01:09:45 %S A204540 2,3,4,6,14,1760,39046 %N A204540 Numbers k whose basins (as defined in A204539) equal 1. %C A204540 Only seven such numbers are known. Referring to A204539, we cannot be certain that these are the only numbers k with the property basin(k) = 1, but there are no others for k less than 12,000,000. Furthermore the average value of basin(k) is approximately equal to k/3 for large values of k, which makes it extremely unlikely that another one will ever be found. %C A204540 For unknown reasons, all integers > 5 with basin equal to 1 or 2 are even. See A185001 for the list of known numbers with basin = 2. %H A204540 Mark Dukes, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL24/Dukes/dukes3.html">Fagan's Construction, Strange Roots, and Tchoukaillon Solitaire</a>, Journal of Integer Sequences, Vol. 24 (2021), Article 21.7.1. %H A204540 Mark Dukes, <a href="https://arxiv.org/abs/2202.02381">Fagan's Construction, Strange Roots, and Tchoukaillon Solitaire</a>, arXiv:2202.02381 [math.NT], 2022. %t A204540 (* First run the program for A204539 to define basin *) Select[Range[1000], basin[#] == 1 &] (* _Alonso del Arte_, Jan 19 2012 *) %Y A204540 Cf. A204539, A185001. %K A204540 nonn,more %O A204540 1,1 %A A204540 _Colm Fagan_, Jan 16 2012