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Triangle T(n,k) read by rows: T(n,k)=1 if the row index n is prime or <=1, otherwise T(n,k) = T(n-1,k)+T(n-1,k-1).
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%I #5 Mar 30 2012 17:34:34

%S 1,1,1,1,1,1,1,1,1,1,1,2,2,2,1,1,1,1,1,1,1,1,2,2,2,2,2,1,1,1,1,1,1,1,

%T 1,1,1,2,2,2,2,2,2,2,1,1,3,4,4,4,4,4,4,3,1,1,4,7,8,8,8,8,8,7,4,1,1,1,

%U 1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1

%N Triangle T(n,k) read by rows: T(n,k)=1 if the row index n is prime or <=1, otherwise T(n,k) = T(n-1,k)+T(n-1,k-1).

%C Row sums are: 1, 2, 3, 4, 8, 6, 12, 8, 16, 32, 64, 12, 24, 14, 28, 56,...

%e 1;

%e 1, 1;

%e 1, 1, 1;

%e 1, 1, 1, 1;

%e 1, 2, 2, 2, 1;

%e 1, 1, 1, 1, 1, 1;

%e 1, 2, 2, 2, 2, 2, 1;

%e 1, 1, 1, 1, 1, 1, 1, 1;

%e 1, 2, 2, 2, 2, 2, 2, 2, 1;

%e 1, 3, 4, 4, 4, 4, 4, 4, 3, 1;

%e 1, 4, 7, 8, 8, 8, 8, 8, 7, 4, 1;

%e 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;

%e 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1;

%e 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;

%e 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1;

%e 1, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 1;

%t Clear[p, x, n, a];

%t p[x, 0] = 1; p[x, 1] = ((x + 1)); p[x, 2] = ((x^2 + x + 1));

%t p[x_, n_] := p[x, n] = If[PrimeQ[n], Sum[x^i, {i, 0, n}], (x + 1)*p[x, n - 1]];

%t a = Table[CoefficientList[FullSimplify[p[x, n]], x], {n, 0, 15}];

%t Flatten[a]

%K nonn,tabl,easy

%O 0,12

%A _Roger L. Bagula_, Feb 27 2009