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 A132293 #18 Nov 03 2023 17:02:16 %S A132293 1,4,3,4,5,6 %N A132293 Maximal number of right angles in an n-gon. %C A132293 A proper definition is needed for this sequence. %C A132293 Conjecture from _R. J. Mathar_, Mar 07 2008, Apr 21 2008: (Start) %C A132293 The correct sequence is a(n)=A014681(n-1), because a polyomino with a zigzag "stair" shape along a diagonal provides a solution where the number of right angles equals the number of edges: %C A132293 ┌─────────┐ %C A132293 |. . . . .| %C A132293 | ┘ %C A132293 |. . . . . %C A132293 | %C A132293 |. .| %C A132293 | ┌─┘ %C A132293 |.| %C A132293 └─┘ %C A132293 (End) %C A132293 Possibly an incorrect version of A049008. - _Michal Paulovic_, Sep 27 2023 %e A132293 The first (n=3) integer in this sequence is 1 because a triangle cannot have more than one right angle. %Y A132293 Cf. A049008. %K A132293 nonn,more,uned,obsc %O A132293 3,2 %A A132293 Asher Stuhlman (asherstuhlman(AT)gmail.com), Nov 06 2007