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 A180746 #16 Aug 29 2020 07:59:21
%S A180746 1,3,6,10,16,23,31,40,51,63,77,93,111,130,151,173,196,220,247,275,306,
%T A180746 338,371,407,445,487,530,574,620,667,715,764,818,874,931,990,1052,
%U A180746 1115,1179,1245,1312,1381,1452,1524,1600,1677,1756,1837,1920,2004,2090,2178
%N A180746 Partial sums of A004144.
%F A180746 a(n) = Sum_{i=1..n} A004144(i).
%t A180746 fQ[n_] := If[n > 1, First@ Union@ Mod[ First@# & /@ FactorInteger@ n, 4] != 1, True]; Accumulate@ Select[ Range@ 90, fQ]
%Y A180746 Cf. A004144.
%K A180746 nonn
%O A180746 1,2
%A A180746 _Jonathan Vos Post_, Sep 19 2010
%E A180746 a(21) and a(50) corrected by _Georg Fischer_, Aug 29 2020