OFFSET
1,1
COMMENTS
Corresponding k's: 1, 6, 15, 50, 78, 219, 4803, 5303, 6973, 8261, 8968, 13058, 13972, 18210, 27426, 41167, ...,.
FORMULA
a(n) = A112662(n)^(1/3).
MATHEMATICA
Composite[n_Integer] := FixedPoint[n + PrimePi@# + 1 &, n + PrimePi@n + 1]; SemiPrimePi[n_] := Sum[PrimePi[n/Prime@i] - i + 1, {i, PrimePi@Sqrt@n}]; SemiPrime[n_] := Block[{e = Floor[Log[2, n] + 1], a, b}, a = 2^e; Do[b = 2^p; While[SemiPrimePi[a] < n, a = a + b]; a = a - b/2, {p, e, 0, -1}]; a + b/2]; lst = {}; Do[c = Composite@n + SemiPrime@n; If[IntegerQ[c^(1/3)], Print[c]], {n, 10^7}]; lst (* Robert G. Wilson v *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, May 01 2006
STATUS
approved