%I #2 Mar 30 2012 17:34:04
%S 0,0,2,0,0,3,0,2,3,4,0,0,0,4,5,0,2,3,4,5,6,0,0,3,0,5,6,7,0,2,0,4,5,6,
%T 7,8,0,0,3,4,0,6,7,8,9,0,2,3,4,5,6,7,8,9,10,0,0,0,0,5,0,7,8,9,10,11,0,
%U 2,3,4,5,6,7,8,9,10,11,12,0,0,3,4,5,6,0,8,9,10,11,12,13,0,2,0,4,0,6,7,8,9
%N Square array read by antidiagonals: T(n,k)=0 if k is a divisor of n, otherwise T(n,k)=k.
%C Observation: Column k is the sequence defined as: Period k: repeat (k-1 numbers k together with zero).
%C Note that the positive terms in row n are the non-divisors of n (See also A173540 and A173541).
%e Array begins:
%e 0,2,3,4,5,6,7,8,9,10,11,12;
%e 0,0,3,4,5,6,7,8,9,10,11;
%e 0,2,0,4,5,6,7,8,9,10;
%e 0,0,3,0,5,6,7,8,9;
%e 0,2,3,4,0,6,7,8;
%e 0,0,0,4,5,0,7;
%e 0,2,3,4,5,6;
%e 0,0,3,0,5;
%e 0,2,0,4;
%e 0,0,3;
%e 0,2;
%e 0;
%Y Cf. A007978, A173540, A173541.
%K easy,nonn,tabl
%O 1,3
%A _Omar E. Pol_, May 25 2010