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 A249727 #12 Feb 22 2020 20:54:24
%S A249727 1,1,1,2,1,2,1,2,3,1,2,3,1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4,5,1,
%T A249727 2,3,4,5,1,2,3,4,5,6,1,2,3,4,5,6,1,2,3,4,5,6,1,2,3,4,5,6,1,2,3,4,5,6,
%U A249727 7,1,2,3,4,5,6,7,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8,9
%N A249727 Start with a(1) = 1; then numbers 1 .. primepi(2), followed by numbers 1 .. primepi(3), and then numbers 1 .. primepi(4), ..., etc, where A000720 gives primepi.
%C A249727 Can be used to construct the irregular table A249809.
%C A249727 This is a fractal sequence; i.e., the removal of the first occurrence of each term in A249727 leaves A249727, so that the sequence contains itself infinitely many times. The corresponding interspersion is A272616. - _Clark Kimberling_, May 12 2016
%H A249727 Antti Karttunen, <a href="/A249727/b249727.txt">Table of n, a(n) for n = 1..10016</a>
%t A249727 Flatten[Table[Range[PrimePi[n]], {n, 2, 100}]]
%t A249727 (* _Clark Kimberling_, May 14 2016 *)
%o A249727 (Scheme) (define (A249727 n) (if (= 1 n) 1 (- n (+ 1 (A046992 (- (A249728 n) 1))))))
%Y A249727 Cf. A000720, A046992, A249728, A249809, A272616.
%K A249727 nonn
%O A249727 1,4
%A A249727 _Antti Karttunen_, Nov 06 2014