OFFSET
1,2
COMMENTS
EXAMPLE
1/a(1) + 1/a(2) +1/a(3) = 1 +1/2 + 1/3 = 11/6. 11/6 + 1/4 = 25/12; but 25 is composite, so a(4) is not 4. But 11/6 +1/5 = 61/30. And since 61 is prime, then a(4) = 5.
MATHEMATICA
f[l_List] := Sum[1/l[[k]], {k, Length[l]}]; g[l_List] := Block[{k = 1, n}, While[n = Numerator[f[Append[l, k]]]; MemberQ[l, k] || ! (n == 1 || PrimeQ[n]), k++ ]; Append[l, k]]; Nest[g, {}, 72] (* Ray Chandler, Jan 22 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Jan 17 2007
EXTENSIONS
Extended by Ray Chandler, Jan 22 2007
STATUS
approved