A152906 Irregular triangle read by rows, numbers in A007318 repeated three times .
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 1, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, 1, 1, 4, 4, 4, 6, 6, 6, 4, 4, 4, 1, 1, 1, 1, 1, 1, 5, 5, 5, 10, 10, 10, 10, 10, 10, 5, 5, 5, 1, 1, 1, 1, 1, 1, 6, 6, 6, 15, 15, 15, 20, 20, 20, 15, 15, 15, 6, 6, 6, 1, 1, 1, 1, 1, 1, 7, 7, 7, 21, 21, 21, 35, 35
Offset: 0
Examples
Triangle begins : 1,1,1 ; 1,1,1,1,1,1 ; 1,1,1,2,2,2,1,1,1 ; 1,1,1,3,3,3,3,3,3,1,1,1, ; 1,1,1,4,4,4,6,6,6,4,4,4,1,1,1 ; 1,1,1,5,5,5,10,10,10,10,10,10,5,5,5,1,1,1 ; ...
Formula
Sum_{k, 0<=k<=2n}T(n,k)=3*2^(n).
Comments