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Search: id:A144680
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| 1, 2, 3, 3, 5, 7, 4, 7, 1, 1, 14, 5, 9, 15, 21, 25, 6, 11, 19, 28, 36, 41, 7, 13, 23, 35, 47, 57, 63, 8, 15, 27, 42, 58, 73, 85, 92, 9, 17, 31, 49, 69, 89, 107, 121, 129, 10, 19, 35, 56, 80, 105, 129, 150, 166, 175
(list; table; graph; listen)
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OFFSET
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1,2
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COMMENT
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Row sums = A006008: (1, 5, 15, 36, 75, 141, 245, 400,...).
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FORMULA
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Triangle read by rows, lower half of an array formed by A004736 * A144328(transform).
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EXAMPLE
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The array is formed by A004736 * A144328(transform); where A004736 = the natural number decrescendo triangle and A144328 = a crescendo triangle. First few rows of the array =
1, 1, 1, 1, 1, 1,...
2, 3, 3, 3, 3, 3,...
3, 5, 7, 7, 7, 7,...
4, 7, 11, 14, 14, 14,...
5, 9, 15, 21, 25, 25,...
...
Extract the lower half including the diagonal, A004006: (1, 3, 7, 14, 25, 41, 63, 92,...); getting:
1;
2, 3;
3, 5, 7;
4, 7, 11, 14;
5, 9, 15, 21, 25;
6, 11, 19, 28, 36, 41;
7, 13, 23, 35, 47, 57, 63;
8, 15, 27, 42, 58, 73, 85, 92;
9, 17, 31, 49, 69, 89, 107, 121, 129;
10, 19, 35, 56, 80, 105, 129, 150, 166, 175;
...
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CROSSREFS
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A144328, Cf. A006008, A004006
Sequence in context: A121400 A056878 A092557 this_sequence A081493 A077558 A122444
Adjacent sequences: A144677 A144678 A144679 this_sequence A144681 A144682 A144683
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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), Sep 19 2008
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