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 A086826 #26 Feb 16 2025 08:32:50 %S A086826 1,0,1,1,3,4,15,24,82 %N A086826 Number of nonsplittable links (prime or composite) with n crossings. %C A086826 A link L is splittable if we can embed a plane in R^3, disjoint from L, that separates one or more components of L from other components of L. Otherwise L is nonsplittable. %H A086826 S. R. Finch, <a href="/A002863/a002863_4.pdf">Knots, links and tangles</a>, August 8, 2003. [Cached copy, with permission of the author] %H A086826 Stéphane Legendre, <a href="/A086826/a086826_1.pdf">Table of nonsplittable links</a> %H A086826 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SplittableLink.html">Splittable Link</a> %H A086826 <a href="/index/K#knots">Index entries for sequences related to knots</a> %e A086826 a(5)=4 since we have 2 prime knots, as well as the Whitehead link; and the trefoil knot linked with a circle. %e A086826 a(6)=15 since we have 3 prime knots, as well as 2 composite knots (the square & granny knots); 6 prime links; a chain of four circles simply-intertwined; four circles simply-intertwined in the shape of a "T"; three circles, two doubly-intertwined and two simply-intertwined; and the figure-eight knot linked with a circle. %Y A086826 Cf. A086771, A086825. %K A086826 nonn %O A086826 0,5 %A A086826 _Steven Finch_, Aug 07 2003 %E A086826 a(7) and a(8) from _Stéphane Legendre_, Jan 06 2014