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 A189713 #12 Oct 21 2024 20:24:27 %S A189713 1,6,23,56,168,459,1080,2400,5461,12678,28728,63336,138717,303346, %T A189713 663179,1438098,3062730,6450121,13583957,28627773,59954459,124413466, %U A189713 258510987,543867101,1152248068,2428235533,5069886692,10511339217,21696371682,44710463120 %N A189713 Central terms of Zorach additive triangle (cf. A035312). %C A189713 a(n) = A035312(2*n,n). %H A189713 Reinhard Zumkeller, <a href="/A189713/b189713.txt">Table of n, a(n) for n = 0..500</a> %H A189713 A. C. Zorach, <a href="http://www.cazort.net/static/triangle.php">Additive triangle</a> %H A189713 <a href="/A035312/a035312_2.hs.txt">Haskell programs for sequences in connection with Zorach additive triangle</a> %o A189713 (Haskell) -- See link. %Y A189713 Cf. A035311, A035313. %K A189713 nonn %O A189713 0,2 %A A189713 _Reinhard Zumkeller_, Apr 30 2011