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 A236857 #12 Jul 29 2021 15:42:11
%S A236857 0,1,2,2,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,
%T A236857 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
%U A236857 5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6
%N A236857 Each n occurs the least common multiple (LCM) of {1, 2, ..., n} (= A003418(n)) times.
%C A236857 Least k such that A236856(k) >= n.
%C A236857 Zero occurs once at a(0), because A003418(0)=1 by definition.
%C A236857 Useful when computing irregular tables like A238280, as a(n) gives the row index of the n-th term in such sequences. Note that as A238280 begins with row 1, it starts referring to this sequence only from a(1)=1 onward.
%H A236857 Antti Karttunen, <a href="/A236857/b236857.txt">Rows 0..10 of the table, flattened</a>
%e A236857 Can be viewed as an irregular table, where each row n (starting from row zero) contains A003418(n) copies of n:
%e A236857 0;
%e A236857 1;
%e A236857 2, 2;
%e A236857 3, 3, 3, 3, 3, 3;
%e A236857 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4;
%e A236857 ...
%t A236857 Join[{0},Flatten[Table[PadRight[{},LCM@@Range[n],{n}],{n,6}]]] (* _Harvey P. Dale_, Jul 29 2021 *)
%o A236857 (Scheme, with _Antti Karttunen_'s IntSeq-library)
%o A236857 (define A236857 (LEAST-GTE-I 0 0 A236856))
%Y A236857 Cf. A003418, A084556, A236856, A236858.
%K A236857 nonn,tabf
%O A236857 0,3
%A A236857 _Antti Karttunen_, Feb 27 2014