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 A075274 #25 Mar 09 2025 12:29:59 %S A075274 2,3,2,5,4,7,16,9,25,55,24,91,196,70,336,714,216 %N A075274 Number of reachable arrangements of coins in the game Blet starting with 2n coins that achieve the maximum number of heads. %C A075274 Rodriguez Villegas, Sadun, and Voloch (2002) prove that the maximum number of heads achievable is A047206(n). - _Pontus von Brömssen_, Mar 08 2025 %H A075274 Michael S. Branicky, <a href="/A075274/a075274.py.txt">Python program for OEIS A075274</a> %H A075274 F. Rodriguez Villegas, L. Sadun and J. F. Voloch, <a href="https://www.jstor.org/stable/3072397">Blet: a mathematical puzzle</a>, Amer. Math. Monthly, 109 No.8 (2002), 729-740. %e A075274 For 4 coins, starting from HTHT we can reach THTT, HHTH, TTTH, THHH, and no others. Of these, two arrangements HHTH and THHH achieve the maximum of 3 heads, so a(2) = 2. %o A075274 (Python) # see linked program %Y A075274 Cf. A047206, A075273, A381812. %K A075274 nonn,more %O A075274 2,1 %A A075274 _N. J. A. Sloane_, Oct 12 2002 %E A075274 Offset corrected by _Michel Marcus_, Sep 30 2017 %E A075274 a(16)-a(18) from and name clarified by _Sean A. Irvine_, Feb 14 2025