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 A338740 #5 Nov 06 2020 09:22:45 %S A338740 0,0,0,0,2,4,14,28,70,140,310,621,1302,2607,5335,10675,21593 %N A338740 Number of hairpin compositions of n. %C A338740 A hairpin composition with t parts is a composition that is true-palindromic except for a part-sequence in the center of length at least 1 but no more than t-2. [Shapcott p. 46] %H A338740 Caroline Shapcott, <a href="https://ajc.maths.uq.edu.au/pdf/60/ajc_v60_p035.pdf">An introduction to true-palindromic compositions</a>, Australasian Journal of Combinatorics, Volume 60(1) (2014), Pages 35-49. %Y A338740 Cf. A002113, A004086, A056964. %Y A338740 Cf. A016116 (symmetric compositions), A338739. %K A338740 nonn,base,more %O A338740 1,5 %A A338740 _Michel Marcus_, Nov 06 2020