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A092081
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Triangle of certain double factorials.
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1
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1, 1, 2, 1, 3, 8, 1, 4, 15, 48, 1, 5, 24, 105, 384, 1, 6, 35, 192, 945, 3840, 1, 7, 48, 315, 1920, 10395, 46080, 1, 8, 63, 480, 3465, 23040, 135135, 645120, 1, 9, 80, 693, 5760, 45045, 322560, 2027025, 10321920, 1, 10, 99, 960, 9009, 80640, 675675, 5160960
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| This is the rectangular array A(3;m,n) := (2*n+m)!!/m!!, m >= 0, n >= 0, read by SW-NE diagonals. For n!! see A006882 (double factorials).
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LINKS
| W. Lang, First 9 rows.
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FORMULA
| a(m, n)=(n+m)!!/(m-n)!!, 0<=n<=m, else 0, with 0!! := 1.
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CROSSREFS
| Diagonals give: A000165 (double factorials of 2*n), A001147(n+1), A002866, A051577-83.
Columns give: A000012 (powers of 1), A000027 (naturals >=2), A005563, 3*A077415, for n=0..3.
Sequence in context: A019224 A053190 A135299 * A203997 A057740 A194505
Adjacent sequences: A092078 A092079 A092080 * A092082 A092083 A092084
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KEYWORD
| nonn,easy,tabl
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AUTHOR
| Wolfdieter Lang (wolfdieter.lang_AT_physik_DOT_uni-karlsruhe_DOT_de), Mar 19 2004
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