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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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1
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OFFSET
| 0,3
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REFERENCES
| Alan Sutcliffe, Divisors and Common Factors in Sets of Integers, awaiting publication.
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FORMULA
| (n-1)*2^(n-3+2^(n-1))
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EXAMPLE
| 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
| 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: A012209 A172286 A129348 * A193269 A088386 A093584
Adjacent sequences: A087081 A087082 A087083 * A087085 A087086 A087087
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KEYWORD
| easy,nonn
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AUTHOR
| Alan Sutcliffe (alansut(AT)ntlworld.com), Aug 13 2003
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