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 A226470 #13 Jun 10 2020 17:41:26
%S A226470 0,0,7,15,26,22,49,45,100,124,83,59,222,242,173,153,392,440,495,471,
%T A226470 322,350,281,773,876,820,1019,931,646,762,597,561,1552,1648,1751,1727,
%U A226470 1930,2022,1857,1789,1396,1484,1379,1163,1102,994,3197,3273,3480,3496,3391,3847,4082
%N A226470 a(n) = n^2 XOR triangular(n), where XOR is the bitwise logical exclusive-or operator.
%F A226470 a(n) = A000290(n) XOR A000217(n).
%e A226470 a(2) = 2^2 xor 2*3/2 = 4 xor 3 = 7.
%t A226470 Table[BitXor[n^2,(n(n+1))/2],{n,0,60}] (* _Harvey P. Dale_, Aug 11 2017 *)
%o A226470 (Python)
%o A226470 for n in range(99):
%o A226470 print((n*n) ^ (n*(n+1)//2), end=", ")
%Y A226470 Cf. A000290, A000217.
%K A226470 nonn,base
%O A226470 0,3
%A A226470 _Alex Ratushnyak_, Jun 08 2013