login
Self-describing sequence: a(n) gives the number of integers in the sequence which are < a(n)^2.
0

%I #10 May 27 2021 01:37:11

%S 0,1,3,9,10,11,12,13,14,81,100,121,144,169,196,197,198,199,200,201,

%T 202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,

%U 219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236

%N Self-describing sequence: a(n) gives the number of integers in the sequence which are < a(n)^2.

%C Earliest strictly increasing sequence satisfying a(a(n))=a(n)^2. - _Benoit Cloitre_, May 26 2021

%e There are 0 integer in the sequence which are < 0^2; there is only 1 integer < 1^2 (this is "0", which is < 1); there are 3 integers < 3^2 (they are 0,1,3 which are < 9); there are 9 integers < 81 (0,1,3,9,10,11,12,13,14); etc.

%K easy,nonn

%O 0,3

%A _Eric Angelini_, Feb 01 2006