OFFSET
1,2
COMMENTS
For odd numbers the intersection is empty.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
EXAMPLE
For n=35, 2n=70; divisors={1,2,5,7,10,14,35,70}; differences={1,3,2,3,4,21,35}; intersection={1,2,35}, so a(35)=3.
MATHEMATICA
a[n_ ] := Length[Intersection[Drop[d=Divisors[2n], 1]-Drop[d, -1], d]]
Table[Length[Intersection[Divisors[2n], Differences[Divisors[2n]]]], {n, 110}] (* Harvey P. Dale, Nov 22 2015 *)
PROG
(PARI)
A060764(n) = { my(divs=divisors(n), diffs=vecsort(vector(#divs-1, i, divs[i+1]-divs[i]), , 8), c=#divs); for(i=1, #diffs, if(!(n%diffs[i]), c--)); (c); };
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Apr 23 2001
EXTENSIONS
Edited by Dean Hickerson, Jan 22 2002
STATUS
approved