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 A274764 #8 Dec 15 2016 17:10:42 %S A274764 1,20,962,75080,8133732,1127589120,190416834360,37902843124640, %T A274764 8686847271179984,2252403871470920960,651771144516905730048, %U A274764 208193858907016903262208,72758882836839703611703296,27613191886304138293279719424,11308972154842887758316960743424,4971172331379604809443266242019328 %N A274764 Number of linear extensions of the one-level grid poset G[(1^n), (1^(n-1)), (1^(n-1))]. %C A274764 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 Catalan number A000108(n), 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) and the number of linear extensions of the one-level grid poset G[(1^n), (1^(n-1)), (0^(n-1))] is given by A274763(n). %H A274764 Ran Pan, <a href="http://www.math.ucsd.edu/~projectp/problems/p1.html">Problem 1</a>, Project P. %H A274764 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 A274764 Cf. A000108, A274644, A274763. %K A274764 nonn %O A274764 1,2 %A A274764 _Ran Pan_, Jul 05 2016