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 A140823 #27 Sep 30 2024 04:48:30
%S A140823 2,3,4,5,6,7,8,9,10,11,12,13,14,15,17,18,19,20,21,22,23,24,25,26,27,
%T A140823 28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,
%U A140823 51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74
%N A140823 Integers that are not perfect fourth powers.
%C A140823 First differs from A046100 at {32, 48, 64, 80, 96, 112, 144, 160, 162, ...}.
%H A140823 A. J. dos Reis and D. M. Silberger, <a href="http://www.jstor.org/stable/2691513">Generating nonpowers by formula</a>, Math. Mag., 63 (1990), 53-55.
%F A140823 {a(n) in A000027 and a(n) not in A000583}.
%t A140823 Module[{nn=100,fp},fp=Floor[Surd[nn,4]];Complement[Range[nn],Range[ fp]^4]] (* _Harvey P. Dale_, Dec 09 2013 *)
%o A140823 (Python)
%o A140823 from sympy import integer_nthroot
%o A140823 def A140823(n): return n+(k:=integer_nthroot(n,4)[0])+int(n>=(k+1)**4-k) # _Chai Wah Wu_, Jun 17 2024
%Y A140823 Cf. A000037, A000583, A007412, A046100.
%K A140823 easy,nonn
%O A140823 1,1
%A A140823 _Jonathan Vos Post_, Jul 17 2008