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 A321127 #12 Apr 10 2019 21:55:17 %S A321127 0,1,0,2,2,0,5,8,3,0,10,24,21,8,1,0,17,56,80,64,30,8,1,0,26,110,220, %T A321127 270,220,122,45,10,1,0,37,192,495,820,952,804,497,220,66,12,1,0,50, %U A321127 308,973,2030,3059,3472,3017,2004,1001,364,91,14,1 %N A321127 Irregular triangle read by rows: row n gives the coefficients in the expansion of ((x + 1)^(2*n) + (x^2 - 1)*(2*(x + 1)^n - 1))/x. %C A321127 These are the coefficients of the Kauffman bracket polynomial evaluated at the shadow diagram of the two-bridge knot with Conway's notation C(n,n). Hence, T(n,k) gives the corresponding number of Kauffman states having exactly k circles. %D A321127 Louis H. Kauffman, Formal Knot Theory, Princeton University Press, 1983. %H A321127 Michael De Vlieger, <a href="/A321127/b321127.txt">Table of n, a(n) for n = 0..14282</a> (rows 0 <= n <= 120, flattened). %H A321127 Louis H. Kauffman, <a href="https://doi.org/10.1016/0040-9383(87)90009-7">State models and the Jones polynomial</a>, Topology Vol. 26 (1987), 395-407. %H A321127 Kelsey Lafferty, <a href="https://scholar.rose-hulman.edu/rhumj/vol14/iss2/7/">The three-variable bracket polynomial for reduced, alternating links</a>, Rose-Hulman Undergraduate Mathematics Journal Vol. 14 (2013), 98-113. %H A321127 Matthew Overduin, <a href="https://www.math.csusb.edu/reu/OverduinPaper.pdf">The three-variable bracket polynomial for two-bridge knots</a>, California State University REU, 2013. %H A321127 Franck Ramaharo, <a href="https://arxiv.org/abs/1902.08989">A generating polynomial for the two-bridge knot with Conway's notation C(n,r)</a>, arXiv:1902.08989 [math.CO], 2019. %H A321127 Wikipedia, <a href="https://en.wikipedia.org/wiki/2-bridge_knot">2-bridge knot</a> %H A321127 Wikipedia, <a href="https://en.wikipedia.org/wiki/Bracket_polynomial">Bracket polynomial</a> %F A321127 T(n,k) = 0 if k = 0, n^2 + 1 if k = 1, and C(2*n, k + 1) - 2*(C(n, k + 1) + C(n, k - 1)) otherwise. %F A321127 T(n,1) = A002522(n). %F A321127 T(n,2) = A300401(n,n). %F A321127 T(n,n) = A001791(n) + A005843(n) - A063524(n). %F A321127 T(n,k) = A094527(n,k-n+1) if n + 1 < k < 2*n and n > 2. %F A321127 G.f.: x*(1 - (1 + x + x^2)*y + (1 + x)*(2 - x^2)*y^2)/((1 - y)*(1 - y - x*y)*(1 - (1 + x)^2*y)). %F A321127 E.g.f.: (exp((1 + x)^2*y) - (exp(x) + 2*exp((1 + x)*y))*(1 - x^2))/x. %e A321127 Triangle begins: %e A321127 n\k | 0 1 2 3 4 5 6 7 8 9 11 12 %e A321127 ----+---------------------------------------------------- %e A321127 0 | 0 1 %e A321127 1 | 0 2 2 %e A321127 2 | 0 5 8 3 %e A321127 3 | 0 10 24 21 8 1 %e A321127 4 | 0 17 56 80 64 30 8 1 %e A321127 5 | 0 26 110 220 270 220 122 45 10 1 %e A321127 6 | 0 37 192 495 820 952 804 497 220 66 12 1 %e A321127 ... %t A321127 row[n_] := CoefficientList[Expand[((x + 1)^(2*n) + (x^2 - 1)*(2*(x + 1)^n - 1))/x], x]; Array[row, 12, 0] // Flatten %o A321127 (Maxima) T(n, k) := if k = 1 then n^2 + 1 else ((4*k - 2*n)/(k + 1))*binomial(n + 1, k) + binomial(2*n, k + 1)$ %o A321127 create_list(T(n, k), n, 0, 12, k, 0, max(2*n - 1, n + 1)); %Y A321127 Row sums: A000302. %Y A321127 Row 1 is row 2 in A300453. %Y A321127 Row 2 is also row 2 in A300454 and A316659. %Y A321127 Cf. A299989, A300184, A300192, A316989. %K A321127 nonn,easy,tabf %O A321127 0,4 %A A321127 _Franck Maminirina Ramaharo_, Nov 19 2018