A087084 Number of integer elements in the subsets of the subsets of the integers 1 to n.

0, 0, 2, 32, 1536, 1048576, 171798691840, 1770887431076116955136, 76223250190290215815795912064716079366144

Offset

0,3

References

Alan Sutcliffe, Divisors and Common Factors in Sets of Integers, awaiting publication.

Links

Table of n, a(n) for n=0..8.

Formula

(n-1)*2^(n-3+2^(n-1))

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.

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: A172286 A129348 A280211 * A193269 A088386 A329928

Adjacent sequences: A087081 A087082 A087083 * A087085 A087086 A087087

Keyword

easy,nonn

Author

Alan Sutcliffe (alansut(AT)ntlworld.com), Aug 13 2003

Status

approved