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 A120245 #26 Jun 24 2025 05:49:57
%S A120245 1,2,3,3,4,5,4,5,6,6,4,5,6,6,7,5,6,7,7,8,9,6,7,8,8,9,10,9,5,6,7,7,8,9,
%T A120245 8,9,6,7,8,8,9,10,9,10,11,7,8,9,9,10,11,10,11,12,12,7,8,9,9,10,11,10,
%U A120245 11,12,12,10,5,6,7,7,8,9,8,9,10,10,8,9,6,7,8,8,9,10,9,10,11,11,9,10,11,7,8
%N A120245 a(1) = 1. a(m(m+1)/2 + k) = a(m) + a(k), 1 <= k <= m+1, m >= 1.
%H A120245 Kevin Ryde, <a href="/A120245/b120245.txt">Table of n, a(n) for n = 1..10011</a>
%H A120245 Michael De Vlieger, <a href="/A120245/a120245.png">Annotated fan-style heat map of a(n)</a>, n = 1..3321, showing n = k(k+1)/2..(k+1)(k+2)/2-1 in semicircular row k, where purples and blues indicate smallest values and reds and magentas largest values in the sequence.
%H A120245 Kevin Ryde, <a href="/A120244/a120244.gp.txt">PARI/GP Code</a>
%t A120245 nn = 12; a[1] = 1; Do[Set[j, a[m] + a[k]]; Set[a[m (m + 1)/2 + k], j], {m, nn}, {k, m + 1}]; Array[a, # (# + 1)/2] &[nn + 1] (* _Michael De Vlieger_, Aug 23 2022 *)
%o A120245 (PARI) \\ See links.
%Y A120245 Cf. A120244, A120246, A064064.
%K A120245 easy,nonn
%O A120245 1,2
%A A120245 _Leroy Quet_, Jun 12 2006
%E A120245 Extended by _Ray Chandler_, Jun 19 2006