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 A018124 #12 Jul 08 2025 06:27:25 %S A018124 1,1,2,2,3,4,5,7,9,12,16,21,28,37,49,64,84,111,147,194,256,338,446, %T A018124 588,776,1024,1351,1783,2353,3104,4096,5405,7132,9410,12417,16384, %U A018124 21619,28526,37641,49667,65536,86475 %N A018124 Powers of fifth root of 4 rounded to nearest integer. %o A018124 (Python) %o A018124 from gmpy2 import iroot_rem %o A018124 def A018124(n): %o A018124 i, j = iroot_rem(1<<(n<<1),5) %o A018124 return int(i)+int(j<<5>=10*i*((i*((i*(i+1)<<1)+1)<<2)+1)+1) # _Chai Wah Wu_, Jun 20 2024 %Y A018124 Cf. A005533. %K A018124 nonn %O A018124 0,3 %A A018124 _N. J. A. Sloane_