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A104570
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Triangle read by rows: T(i,j) is the (i,j)-entry (1 <= j <= i) of the product R*Q of the infinite lower triangular matrices R = [1; 1,1; 1,1,1; 1,1,1,1; ...] and Q = [1; 1,3; 1,3,1; 1,3,1,3; ...].
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2
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1, 2, 3, 3, 6, 1, 4, 9, 2, 3, 5, 12, 3, 6, 1, 6, 15, 4, 9, 2, 3, 7, 18, 5, 12, 3, 6, 1, 8, 21, 6, 15, 4, 9, 2, 3, 9, 24, 7, 18, 5, 12, 3, 6, 1, 10, 27, 8, 21, 6, 15, 4, 9, 2, 3, 11, 30, 9, 24, 7, 18, 5, 12, 3, 6, 1, 12, 33, 10, 27, 8, 21, 6, 15, 4, 9, 2, 3, 13, 36, 11, 30, 9, 24, 7, 18, 5, 12, 3, 6
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OFFSET
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1,2
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LINKS
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FORMULA
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Even columns (offset) = 1, 2, 3, ...; while odd columns = 3, 6, 9, ...
T(i,j) = i-j+1 if j <= i and j is odd; 3(i-j+1) if j <= i and j is even. - Emeric Deutsch, Mar 23 2005
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EXAMPLE
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First few rows of the triangle:
1;
2, 3;
3, 6, 1;
4, 9, 2, 3;
...
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MAPLE
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T:=proc(i, j) if j>i then 0 elif j mod 2 = 1 then i-j+1 else 3*(i-j+1) fi end:for i from 1 to 14 do seq(T(i, j), j=1..i) od; # yields sequence in triangular form # Emeric Deutsch, Mar 23 2005
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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