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A120641
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Number of partitions of n into distinct double-free parts.
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0
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1, 1, 1, 2, 3, 2, 4, 5, 5, 7, 8, 10, 12, 14, 17, 20, 24, 26, 31, 38, 45, 50, 57, 68, 77, 88, 101, 116, 132, 151, 170, 194, 222, 247, 281, 318, 356, 399, 452, 509, 567, 635, 709, 794, 885, 983, 1094, 1222, 1358, 1504, 1671, 1854, 2050, 2264, 2505, 2771, 3060, 3370
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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LINKS
| Eric Weisstein's World of Mathematics, Double-Free Set
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EXAMPLE
| a(10) = #{10, 9+1, 8+2, 7+3, 6+4, 5+4+1, 5+3+2} = 7;
a(11) = #{11, 10+1, 9+2, 8+3, 7+4, 7+3+1, 6+5, 6+4+1} = 8.
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CROSSREFS
| Cf. A000009, A050291.
Sequence in context: A090321 A174625 A178853 * A008666 A140503 A176789
Adjacent sequences: A120638 A120639 A120640 * A120642 A120643 A120644
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 17 2006
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