A249727 - OEIS

%I #12 Feb 22 2020 20:54:24

%S 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 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 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 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 Can be used to construct the irregular table A249809.

%C 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 Antti Karttunen, <a href="/A249727/b249727.txt">Table of n, a(n) for n = 1..10016</a>

%t Flatten[Table[Range[PrimePi[n]], {n, 2, 100}]]

%t (* _Clark Kimberling_, May 14 2016 *)

%o (Scheme) (define (A249727 n) (if (= 1 n) 1 (- n (+ 1 (A046992 (- (A249728 n) 1))))))

%Y Cf. A000720, A046992, A249728, A249809, A272616.

%K nonn

%O 1,4

%A _Antti Karttunen_, Nov 06 2014