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Search: id:A089647
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| A089647 |
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Number of triangular partitions of n. |
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+0
1
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| 1, 1, 1, 2, 2, 4, 6, 8, 12, 18, 26, 37, 54, 76, 111, 156, 221, 310, 438, 608, 850, 1178, 1633, 2251, 3104, 4257, 5837, 7972, 10866, 14772, 20042, 27121, 36625, 49356, 66366, 89077, 119319, 159547, 212942, 283753, 377423, 501274, 664639, 879963
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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Number of ways of writing n as a sum [p(1,1) + p(1,2) + ... + p(1,k)] + [p(2,1) + ... + p(2,k-1)] + [p(3,1) + ... + p(3,k-2)] + ... + [p(k,1)] for some k =0, 1, 2, ..., so that in the triangular array {p(i,j)} the numbers are nonincreasing along rows and columns. All the p(i,j) are >= 1.
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LINKS
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Jon Schoenfield, Table of n, a(n) for n = 0..64
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EXAMPLE
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a(8)=12, as seen from the following list:
8...61..51..41..52..42..32..43..33..311.211.221
....1...2...3...1...2...3...1...2...11..21..11.
....................................1...1...1..
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CROSSREFS
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Cf. A089299.
Sequence in context: A018129 A091915 A123862 this_sequence A145465 A153958 A153964
Adjacent sequences: A089644 A089645 A089646 this_sequence A089648 A089649 A089650
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KEYWORD
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nonn,nice
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AUTHOR
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John W. Layman (layman(AT)math.vt.edu), Jan 02 2004
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EXTENSIONS
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More terms from Jon E. Schoenfield (jonscho(AT)hiwaay.net), Aug 06 2006
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