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Search: id:A104572
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| A104572 |
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Triangle read by rows: T(i,j) is the (i,j)-entry (1<=j<=i) of the product A*B of the infinite lower triangular matrices A = [1; 3, 1;5, 3, 1; 7, 5, 3, 1;...] and B=[1; 2,1; 1,2,1; 2,1,2,1;...]. |
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+0
1
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| 1, 5, 1, 12, 5, 1, 22, 12, 5, 1, 35, 22, 12, 5, 1, 51, 35, 22, 12, 5, 1, 70, 51, 35, 22, 12, 5, 1, 92, 70, 51, 35, 22, 12, 5, 1, 117, 92, 70, 51, 35, 22, 12, 5, 1, 145, 117, 92, 70, 51, 35, 22, 12, 5, 1, 176, 145, 117, 92, 70, 51, 35, 22, 12, 5, 1, 210, 176, 145, 117, 92, 70, 51, 35
(list; table; graph; listen)
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OFFSET
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1,2
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FORMULA
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T(i, j)=(i-j+1)(3i-3j+2)/2 for 1<=j<=i. - Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 23 2005
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EXAMPLE
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The first few rows are:
1;
5, 1;
12, 5, 1;
22, 12, 5, 1;
35, 22, 12, 5, 1;
...
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MAPLE
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T:=proc(i, j) if j<=i then (i-j+1)*(3*i-3*j+2)/2 else 0 fi end: for i from 1 to 13 do seq(T(i, j), j=1..i) od; # yields sequence in traingular form (Deutsch)
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CROSSREFS
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Row sums yield the pentagonal pyramidal numbers (A002411). Columns (starting from the diagonal entries) are the pentagonal numbers (A000326).
Sequence in context: A132000 A132001 A063004 this_sequence A125232 A116923 A062264
Adjacent sequences: A104569 A104570 A104571 this_sequence A104573 A104574 A104575
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KEYWORD
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nonn,tabl
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AUTHOR
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Gary W. Adamson (qntmpkt(AT)yahoo.com), Mar 16 2005
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 23 2005
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