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A127476 Triangle T(n,k) = sum_{j=k..n, gcd(n,j)=1, k|j} phi(k). 0

%I

%S 1,1,0,2,1,0,2,0,2,0,4,2,2,2,0,2,0,0,0,4,0,6,3,4,2,4,2,0,4,0,2,0,4,0,

%T 6,0,6,3,0,4,4,0,6,4,0,4,0,4,0,0,0,6,0,6,0,10,5,6,4,8,2,6,4,6,4,0,4,0,

%U 0,0,4,0,6,0,0,0,10,0

%N Triangle T(n,k) = sum_{j=k..n, gcd(n,j)=1, k|j} phi(k).

%F T(n,k) = sum_{j=k..n} A054521(n,j) * A054522(j,k), product of the two infinite lower triangular matrices.

%F T(n,1) = A000010(n).

%e First few rows of the triangle are:

%e 1;

%e 1, 0;

%e 2, 1, 0;

%e 2, 0, 2, 0;

%e 4, 2, 2, 2, 0;

%e 2, 0, 0, 0, 4, 0;

%e 6, 3, 4, 2, 4, 2, 0;

%e 4, 0, 2, 0, 4, 0, 6, 0;

%e ...

%Y Cf. A054521, A054522, A023896 (row sums), A000010.

%K nonn,tabl

%O 1,4

%A _Gary W. Adamson_, Jan 15 2007

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Last modified April 16 09:04 EDT 2021. Contains 343030 sequences. (Running on oeis4.)