OFFSET
0,2
COMMENTS
Symmetrically, also the number of relations from a set of at most n elements into an n-element set.
FORMULA
a(n) = (2^(n+n^2) - 1)/(2^n - 1) for n > 0 and a(0) = 1.
a(n) ~ 2^(n^2).
a(n) = A275779(n) + 1. - Hugo Pfoertner, May 14 2021
MATHEMATICA
Join[{1}, Table[(2^(n+n^2)-1)/(2^n-1), {n, 13}]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Stefano Spezia, May 13 2021
STATUS
approved