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Search: id:A087084
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| A087084 |
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Number of integer elements in the subsets of the subsets of the integers 1 to n. |
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+0
2
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| 0, 0, 2, 32, 1536, 1048576, 171798691840, 1770887431076116955136, 76223250190290215815795912064716079366144
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OFFSET
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0,3
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REFERENCES
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Alan Sutcliffe, Divisors and Common Factors in Sets of Integers, awaiting publication.
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FORMULA
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(n-1)*2^(n-3+2^(n-1))
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EXAMPLE
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a(3)=32 since the 16 subsets of the sets ( ) (1) (2) (1,2) are ( ) (( )) ((1)) ((2)) ((1,2)) (( ) (1)) (( ) (2)) (( ) (1,2)) ((1) (2)) ((1) (1,2)) ((2) (1,2)) (( ) (1) (2)) (( ) (1) (1,2)) (( ) (2) (1,2)) ((1) (2) (1,2)) (( ) (1) (2) (1,2)) and these contain 32 integer elements.
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CROSSREFS
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A001146 gives the number of subsets of the subsets of the integers 1 to n. A028369 gives the number of subset elements in the subsets of the subsets of the integers 1 to n.
Sequence in context: A012140 A012209 A129348 this_sequence A088386 A093584 A117259
Adjacent sequences: A087081 A087082 A087083 this_sequence A087085 A087086 A087087
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KEYWORD
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easy,nonn
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AUTHOR
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Alan Sutcliffe (alansut(AT)ntlworld.com), Aug 13 2003
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