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 A371388 #21 Mar 21 2024 12:32:48 %S A371388 1,8,15,32,55,72,105,128,171,220,253,312,377,420,495,544,629,720,779, %T A371388 880,945,1056,1173,1248,1375,1508,1593,1736,1827,1980,2139,2240,2409, %U A371388 2584,2695,2880,2997,3192,3393,3520,3731,3864,4085,4312,4455,4692,4935,5088,5341 %N A371388 a(n) = 2*n*floor(n*(1 + sqrt(5))/2) - n^2. Main diagonal of A340429. %H A371388 Paolo Xausa, <a href="/A371388/b371388.txt">Table of n, a(n) for n = 1..10000</a> %F A371388 a(n) = 2*n*A000201(n) - n^2. %t A371388 Array[2 * # * Floor[# * GoldenRatio] - #^2 &, 100] %o A371388 (Python) %o A371388 from math import isqrt %o A371388 def A371388(n): return n*((n+isqrt(5*n**2)&-2)-n) # _Chai Wah Wu_, Mar 21 2024 %Y A371388 Cf. A340429. %Y A371388 Cf. A000201, A001622. %K A371388 nonn,easy %O A371388 1,2 %A A371388 _Paolo Xausa_, Mar 21 2024