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A127472
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Triangle T(n,k) = Sum_{j=k..n, j|n, k|j} phi(j) read by rows, 1<=k<=n.
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1
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1, 2, 1, 3, 0, 2, 4, 3, 0, 2, 5, 0, 0, 0, 4, 6, 3, 4, 0, 0, 2, 7, 0, 0, 0, 0, 0, 6, 8, 7, 0, 6, 0, 0, 0, 4, 9, 0, 8, 0, 0, 0, 0, 0, 6, 10, 5, 0, 0, 8, 0, 0, 0, 0, 4, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 12, 9, 8, 6, 0, 6, 0, 0, 0, 0, 0, 4, 13
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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EXAMPLE
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First few rows of the triangle are;
.1;
.2, 1;
.3, 0, 2;
.4, 3, 0, 2;
.5, 0, 0, 0, 4;
.6, 3, 4, 0, 0, 2;
.7, 0, 0, 0, 0, 0, 6;
.8, 7, 0, 6, 0, 0, 0, 4;
....
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MAPLE
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a := 0 ;
for j from k to n do
if (n mod j = 0 ) and (j mod k =0 ) then
a := a+numtheory[phi](j) ;
end if;
end do;
a ;
end proc:
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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