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 A274645 #17 Dec 15 2016 16:57:23 %S A274645 1,20,1301,177260,41385102,14760468600,7465847167005,5083351577582300, %T A274645 4483012419041095680,4971032496120058085376,6769339545226095791964160, %U A274645 11105730970797793499164966912,21604722570792867452576610648064 %N A274645 Number of linear extensions of the one-level grid poset G[(2^n), (0^(n-1)), (0^(n-1))]. %C A274645 The definition of a one-level grid poset can be found in the Pan links. The number of linear extensions of the one-level grid poset G[(0^n), (0^(n-1)), (0^(n-1))] is given by the Catalan number A000108(n) and the number of linear extensions of the one-level grid poset G[(1^n), (0^(n-1)), (0^(n-1))] is given by A274644(n). %H A274645 Ran Pan, <a href="http://www.math.ucsd.edu/~projectp/problems/p1.html">Problem 1</a>, Project P. %H A274645 Ran Pan, <a href="http://www.math.ucsd.edu/~projectp/problems/solutions/OneLevelGridPoset.pdf">Algorithmic Solution to Problem 1 (and linear extensions of general one-level grid-like posets)</a>, Project P. %Y A274645 Cf. A000108, A274644. %K A274645 nonn %O A274645 1,2 %A A274645 _Ran Pan_, Jun 30 2016