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 A226471 #13 Feb 03 2025 18:58:10 %S A226471 0,1,3,7,15,25,31,63,113,127,189,200,255,381,481,499,511,765,1004, %T A226471 1011,1023,1533,1785,1808,1985,2023,2035,2047,3069,3199,3255,3577, %U A226471 3810,4071,4083,4095,4446,6141,6399,7161,8065,8135,8167,8179,8191,12285,12799,14279,14280 %N A226471 Numbers n such that n^2 XOR triangular(n) is a triangular number. XOR is the bitwise logical exclusive-or operator. %C A226471 Indices of triangular numbers in A226470. Numbers n such that A226470(n) and A226470(n+1) are triangular numbers: 0, 14279, 491279, 16251935, 29358023, 528478271, ... %t A226471 Select[Range[0,15000],OddQ[Sqrt[8*BitXor[#^2,(#(#+1))/2]+1]]&] (* _Harvey P. Dale_, Jul 22 2024 *) %o A226471 (Python) %o A226471 import math %o A226471 for n in range(100000000): %o A226471 a = (n*n) ^ (n*(n+1)//2) %o A226471 r = int(math.sqrt(a*2)) %o A226471 if r*(r+1)==a*2: print(n, end=', ') %Y A226471 Cf. A000217, A000290, A226470, A224218. %K A226471 nonn,base %O A226471 1,3 %A A226471 _Alex Ratushnyak_, Jun 08 2013