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 A194033 #25 Jul 19 2025 16:11:24
%S A194033 1,3,6,2,5,9,10,15,4,8,13,14,20,21,28,7,12,18,19,26,27,35,36,45,11,17,
%T A194033 24,25,33,34,43,44,54,55,66,16,23,31,32,41,42,52,53,64,65,77,78,91,22,
%U A194033 30,39,40,50,51,62,63,75,76,89,90,104,105,120,29
%N A194033 Inverse permutation of A194032; contains every positive integer exactly once.
%H A194033 Zhuorui He, <a href="/A194033/b194033.txt">Table of n, a(n) for n = 1..10000</a>
%F A194033 a(n) = binomial(x + z,2) + y + 1 where x = floor(sqrt(n)), y = n - x^2 and z = min(y,floor(y/2 + 1)). - _Zhuorui He_, Jul 19 2025
%t A194033 (See A194032.)
%o A194033 (PARI) A194033(n)={my(x=sqrtint(n), y=n-x^2, z=min(y,floor(y/2+1))) ;binomial(x+z,2)+y+1} \\ _Zhuorui He_, Jul 19 2025
%Y A194033 Cf. A194032.
%K A194033 nonn
%O A194033 1,2
%A A194033 _Clark Kimberling_, Aug 12 2011
%E A194033 a(63) corrected and a(64) added by _Zhuorui He_, Jul 07 2025