OFFSET
1,1
COMMENTS
This is a very slow-growing sequence: for n <= 1000, a(n) <= 18. The number a(n) * prime(n) is the least number divisible by prime(n) in sequence A092671.
LINKS
Peter Pein, Table of n, a(n) for n = 1..10515
Eric Weisstein's World of Mathematics, Egyptian Fraction
EXAMPLE
a(1) = 3 because 2 = prime(1) and 1/1 + 1/3 = 4/3, whose numerator is divisible by 2.
MATHEMATICA
len=100; a=Table[0, {len}]; done=False; s={0}; n=0; While[ !done, n++; s=Join[s, s+1/n]; ns=Numerator[s]; done=True; Do[If[a[[i]]==0, p=Prime[i]; If[Count[ns, _?(#>0 && Mod[ #, p]==0&)]>0, a[[i]]=n, done=False]], {i, len}]]; a
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Mar 29 2004
STATUS
approved