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 A378287 #7 Nov 21 2024 22:28:03 %S A378287 2,3,4,5,6,7,9,10,11,12,13,14,15,17,18,19,20,21,22,23,24,25,26,28,29, %T A378287 30,31,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53, %U A378287 54,55,56,57,58,59,60,61,62,63,65,66,67,68,69,70,71,72,73 %N A378287 Numbers not of the form m^k for some k>=3. Complement of A076467. %C A378287 Differs from A362147 at a(419). %o A378287 (Python) %o A378287 from sympy import integer_nthroot, mobius %o A378287 def A378287(n): %o A378287 def f(x): return int(n+integer_nthroot(x,4)[0]-sum(mobius(k)*(integer_nthroot(x,k)[0]+integer_nthroot(x,k<<1)[0]-2) for k in range(3,x.bit_length()))) %o A378287 m, k = n, f(n) %o A378287 while m != k: m, k = k, f(k) %o A378287 return m %Y A378287 Cf. A076467, A362147. %K A378287 nonn,easy %O A378287 1,1 %A A378287 _Chai Wah Wu_, Nov 21 2024