login
Rearrangement of natural numbers so that starting with a(n) the concatenation of n numbers gives a composite number.
1

%I #4 Dec 05 2013 19:55:39

%S 4,1,2,3,5,6,7,8,9,10,11,12,14,13,15,16,17,18,19,20,21,22,23,24,25,26,

%T 27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,50,

%U 49,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72

%N Rearrangement of natural numbers so that starting with a(n) the concatenation of n numbers gives a composite number.

%e 4, 12, 235, 3567, etc. are composite.

%Y Cf. A075616.

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Sep 29 2002

%E Corrected and extended by _David Wasserman_, Jan 21 2005