OFFSET
1,2
LINKS
Robert Israel, Table of n, a(n) for n = 1..100
EXAMPLE
a(2)=6 since we can obtain 6 values, i.e., {1, 3/2, 2, 5/2, 3, 4}.
MAPLE
fracs:= {1}:
A[1]:= 1:
for n from 2 to 100 do
fracs:= fracs union {seq(n/i, i=1..n-1)} union {seq(i/n, i=1..n-1)};
A[n]:= nops({seq(seq(fracs[i]+fracs[j], j=1..i), i=1..nops(fracs))});
od:
seq(A[n], n=1..100); # Robert Israel, Apr 26 2015
MATHEMATICA
Table[Length@Union@Flatten@Table[a/b + c/d, {a, n}, {b, n}, {c, n}, {d, n}], {n, 24}]
Table[Length[Union[#[[1]]/#[[2]]+#[[3]]/#[[4]]&/@Tuples[Range[n], {4}]]], {n, 25}] (* Harvey P. Dale, Mar 04 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Resta, May 26 2006
EXTENSIONS
More terms from Harvey P. Dale, Mar 04 2013
a(31) to a(40) from Robert Israel, Apr 26 2015
STATUS
approved