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 A118030 #10 Sep 19 2017 21:54:00
%S A118030 1,2,4,8,12,16,20,28,36,44,52,64,76,88,100,116,132,148,164,184,204,
%T A118030 224,244,264,284,304,324,352,380,408,436,464,492,520,548,584,620,656,
%U A118030 692,728,764,800,836,880,924,968,1012,1056,1100,1144,1188,1240,1292,1344,1396,1448,1500,1552,1604,1656,1708,1760
%N A118030 a(1)=1. a(n) = a(n-1) + (largest integer which is <= n and occurs among the earlier terms of the sequence).
%H A118030 Michael De Vlieger, <a href="/A118030/b118030.txt">Table of n, a(n) for n = 1..5000</a>
%t A118030 a = {1}; Do[k = i + 1; While[Nand[MemberQ[a, k], k <= i + 1], k--]; AppendTo[a, a[[i]] + k], {i, 61}]; a (* _Michael De Vlieger_, Sep 19 2017 *)
%Y A118030 Cf. A118026, A118027, A118028, A118029, A094589.
%K A118030 easy,nonn
%O A118030 1,2
%A A118030 _Leroy Quet_, Apr 10 2006
%E A118030 More terms from Melissa Donovan (msd181(AT)psu.edu), Apr 23 2006