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Array T by antidiagonals: T(h,k)=number of paths consisting of steps from (0,0) to (h,k) such that each step has length 1 directed up or right and no step touches the line y=3x unless x=0 or x=h.
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%I #7 May 11 2021 21:32:52

%S 1,1,1,1,1,1,1,1,2,1,1,2,3,3,1,1,1,3,6,4,1,1,2,3,9,10,5,1,1,3,3,12,19,

%T 15,6,1,1,4,6,15,31,34,21,7,1,1,5,4,15,46,65,55,28,8,1,1,6,9,15,61,

%U 111,120,83,36,9,1,1,7,15,15,76,172,231,203,119,45

%N Array T by antidiagonals: T(h,k)=number of paths consisting of steps from (0,0) to (h,k) such that each step has length 1 directed up or right and no step touches the line y=3x unless x=0 or x=h.

%e Antidiagonals (beginning on row 0): {1}; {1,1}; {1,1,1}; {1,1,2,1}; {1,2,3,3,1}; ...

%Y Cf. A047010 (mirror image).

%K nonn,tabl

%O 0,9

%A _Clark Kimberling_