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 A217943 #23 Aug 02 2014 06:14:09 %S A217943 2,-2,0,2,-2,2,-2,2,-2,0,0,0,2,-2,4,-2,-2,0,2,-2,0,0,0,0,0,2,-2,6,-6, %T A217943 2,-2,0,0,2,-2,0,6,-6,0,0,0,0,2,-2,10,-10,0,2,-2,0,0,0,2,-2,0,0,0,0,0, %U A217943 0,0,0,0,2,-2,20,-10,-4,-6,2,-2,0,0,0,0,2,-2,0,0,0,0,0,0,0,0,0,0,0,2,-2 %N A217943 Triangle read by rows: T(n,k) = 2*C(n-1,k)-C(n,k) for k<n, T(n,n)=-2, where C(n,k) = A216955(n,k). %H A217943 B. Chaffin, J. P. Linderman, N. J. A. Sloane and Allan Wilks, <a href="http://arxiv.org/abs/1212.6102">On Curling Numbers of Integer Sequences</a>, arXiv:1212.6102, Dec 25 2012. %H A217943 B. Chaffin, J. P. Linderman, N. J. A. Sloane and Allan Wilks, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL16/Sloane/sloane3.html">On Curling Numbers of Integer Sequences</a>, Journal of Integer Sequences, Vol. 16 (2013), Article 13.4.3. %H A217943 N. J. A. Sloane, <a href="/A217943/a217943.txt">Rows 2 through 48 of A217943</a> %H A217943 <a href="/index/Cu#curling_numbers">Index entries for sequences related to curling numbers</a> %e A217943 Triangle begins: %e A217943 [2, -2] %e A217943 [0, 2, -2] %e A217943 [2, -2, 2, -2] %e A217943 [0, 0, 0, 2, -2] %e A217943 [4, -2, -2, 0, 2, -2] %e A217943 [0, 0, 0, 0, 0, 2, -2] %e A217943 [6, -6, 2, -2, 0, 0, 2, -2] %e A217943 [0, 6, -6, 0, 0, 0, 0, 2, -2] %e A217943 [10, -10, 0, 2, -2, 0, 0, 0, 2, -2] %e A217943 [0, 0, 0, 0, 0, 0, 0, 0, 0, 2, -2] %e A217943 [20, -10, -4, -6, 2, -2, 0, 0, 0, 0, 2, -2] %e A217943 ... %Y A217943 Cf. A216955. %Y A217943 The nonzero entries in the first column form A216958. %K A217943 sign,tabf %O A217943 2,1 %A A217943 _N. J. A. Sloane_, following a suggestion from _Allan Wilks_, Oct 25 2012