OFFSET
1,5
COMMENTS
Also the number of subsets in the same interval whose product is precisely a square, if 1 is included.
LINKS
Andrew Granville and John Selfridge, Product of integers in an interval, modulo squares, Electronic Journal of Combinatorics, Volume 8(1), 2001.
FORMULA
a(n) = 2^A120254(n).
EXAMPLE
a(5) = 2 because the interval [26,35] contains two sets of such integers: {32} and {27,28,30,35}.
CROSSREFS
KEYWORD
nonn
AUTHOR
Martin Fuller, Jun 13 2006
STATUS
approved