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 A048136 #19 Apr 02 2025 15:16:35
%S A048136 11,22,23,25,29,31,33,41,43,44,46,47,49,50,53,55,58,59,61,62,66,67,69,
%T A048136 71,75,77,79,82,83,86,87,88,89,92,93,94,98,99,100,101,103,106,107,110,
%U A048136 113,115,116,118,121,122,123,124,125,127,129,131,132,134
%N A048136 Tomahawk-nonconstructible n-gons.
%H A048136 Andrew M. Gleason, <a href="http://www.jstor.org/stable/2323624">Angle Trisection, the Heptagon and the Triskaidecagon</a>, American Mathematical Monthly, 95 (1988), 185-194.
%F A048136 A122255(a(n)) = 0: complement of A122254. - _Reinhard Zumkeller_, Aug 29 2006
%o A048136 (Python)
%o A048136 from itertools import count, islice
%o A048136 from sympy import primefactors, totient
%o A048136 def A048136_gen(): # generator of terms
%o A048136 yield from filter(lambda n: not set(primefactors(totient(n))) <= {2,3}, count(3))
%o A048136 A048136_list = list(islice(A048136_gen(),58)) # _Chai Wah Wu_, Apr 02 2025
%Y A048136 Cf. A005109, A048135, A122254, A122255.
%K A048136 nonn
%O A048136 1,1
%A A048136 _David W. Wilson_