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 A153157 #10 Nov 22 2024 01:45:55 %S A153157 16,81,625,1296,2401,10000,14641,20736,28561,38416,50625,83521,104976, %T A153157 130321,160000,194481,234256,279841,331776,456976,614656,707281, %U A153157 810000,923521,1185921,1336336,1500625,1874161,2085136,2313441,2560000,2825761 %N A153157 a(n) = A007916(n)^4. %C A153157 2^4=16,3^4=81,4^4=256=2^8 is not in the sequence,5^4=625,6^4=1296,... %t A153157 Select[Range[2,100],GCD@@Last/@FactorInteger@#==1&]^4 %o A153157 (Python) %o A153157 from sympy import mobius, integer_nthroot %o A153157 def A153157(n): %o A153157 def f(x): return int(n+1-sum(mobius(k)*(integer_nthroot(x,k)[0]-1) for k in range(2,x.bit_length()))) %o A153157 m, k = n, f(n) %o A153157 while m != k: m, k = k, f(k) %o A153157 return m**4 # _Chai Wah Wu_, Nov 21 2024 %Y A153157 Cf. A007916, A153147, A153158, A153159, A153160, A113849. %K A153157 nonn %O A153157 1,1 %A A153157 _Vladimir Joseph Stephan Orlovsky_, Dec 19 2008 %E A153157 Edited by _Ray Chandler_, Dec 22 2008