OFFSET
1,2
COMMENTS
Solutions appear in clusters because of features of diagram visible at A004648. Later clusters are introduced by 6455, 15928, 40073, 100362, 251707, 637235, 4124455, respectively.
Number of solutions in consecutive clusters seem to be as follows: 1,2,4,3,6,1,1,1,6,2,7,3 etc..
MATHEMATICA
ta={{0}}; Do[s=w*fra[Prime[w]/w]; If[ !Greater[s, Log[n]], Print[w]; ta=Append[ta, w]], {w, 1, 1000000}]; ta=Delete[ta, 1]
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Nov 02 2004
STATUS
approved