%I #5 Feb 19 2014 18:20:37
%S 0,0,0,0,2,0,0,0,3,0,0,2,3,4,0,0,0,0,4,5,0,0,2,3,4,5,6,0,0,0,3,0,5,6,
%T 7,0,0,2,0,4,5,6,7,8,0,0,0,3,4,0,6,7,8,9,0,0,2,3,4,5,6,7,8,9,10,0,0,0,
%U 0,0,5,0,7,8,9,10,11,0,0,2,3,4,5,6,7,8,9,10,11,12,0,0,0,3,4,5,6,0,8,9,10,11
%N Triangle read by rows: T(n,k)=k if k is a proper non-divisor of n, otherwise T(n,k)=0 (1<=k<=n).
%C Observation: Note that the k-th column is a sequence where the periodic subset is formed by zero together with k-1 numbers k. For example, the 5th column can be defined as "Period 5: repeat 0,5,5,5,5".
%H Reinhard Zumkeller, <a href="/A173541/b173541.txt">Rows n = 1..125 of triangle, flattened</a>
%F T(n,k) = k * A051731(n,k). - _Reinhard Zumkeller_, Feb 19 2014
%e Triangle begins:
%e 0;
%e 0,0;
%e 0,2,0;
%e 0,0,3,0;
%e 0,2,3,4,0;
%e 0,0,0,4,5,0;
%e 0,2,3,4,5,6,0;
%e 0,0,3,0,5,6,7,0;
%e 0,2,0,4,5,6,7,8,0;
%e 0,0,3,4,0,6,7,8,9,0;
%e 0,2,3,4,5,6,7,8,9,10,0;
%e 0,0,0,0,5,0,7,8,9,10,11,0;
%e 0,2,3,4,5,6,7,8,9,10,11,12,0;
%e 0,0,3,4,5,6,0,8,9,10,11,12,13,0;
%e 0,2,0,4,0,6,7,8,9,10,11,12,13,14,0;
%e 0,0,3,0,5,6,7,0,9,10,11,12,13,14,15,0;
%o (Haskell)
%o a173541 n k = a173541_tabl !! (n-1) !! (n-1)
%o a173541_row n = a173541_tabl !! (n-1)
%o a173541_tabl = zipWith (zipWith (*))
%o a002260_tabl $ map (map (1 -)) a051731_tabl
%o -- _Reinhard Zumkeller_, Feb 19 2014
%Y Cf. A049820, A127093, A173540. Row sums give A024816.
%Y Cf. A002260.
%K easy,nonn,tabl
%O 1,5
%A _Omar E. Pol_, May 25 2010