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 A289713 #9 Sep 02 2017 15:50:04 %S A289713 1,2,9,61,449,3161,21145,136529,862209,5369617,33133481,203119577, %T A289713 1239049729,7528608985,45596026169,275385806881,1659295498241, %U A289713 9977108934689,59881303252297,358815987469673,2146943650081281,12829239786138217,76571416493573849,456525052642949681 %N A289713 The order of the semigroup of orientation-preserving partial transformations on n elements. %C A289713 Row sums of A289710 and of A289711. %H A289713 A. Umar, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL14/Umar/umar2.html">Combinatorial Results for Semigroups of Orientation-Preserving Partial Transformations</a>, J. Int. Seq. 14 (2011) # 11.7.5, Tables 2.1, 2.2 and 2.3. %Y A289713 Cf. A289710, A289711. %K A289713 nonn,easy %O A289713 0,2 %A A289713 _R. J. Mathar_, Sep 02 2017