OFFSET
1,1
COMMENTS
a(n) is surely larger than the n-th, but seems even larger than the (n+1)-th primorial number.
a(n) is neither necessarily squarefree nor it has a specified number of distinct prime-factors.
EXAMPLE
a(3) = 664, 663 = 3*13*17 and 665 = 5*11*19 both have three prime divisors.
MATHEMATICA
lf[x_] := Length[FactorInteger[x]] am[x_] := Abs[MoebiusMu[x]] q[x_] := Apply[Times, Table[Prime[j], {j, 1, x}]] Table[flag=1; Print["#"]; Do[s1=am[n-1]; s2=am[n+1]; If[Equal[s1, 1]&&Equal[s2, 1]&&Equal[lf[n-1], j] &&Equal[lf[n+1], j]&&Equal[flag, 1], Print[{n, j}]; flag=0], {n, q[j], q[j]+...}], {j, 1, 4}]
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Amarnath Murthy, Sep 22 2003
EXTENSIONS
Edited by Labos Elemer, Sep 26 2003
84946016 from Ray Chandler, Oct 09 2003
a(7) and a(8) from Donovan Johnson, Apr 22 2008
a(9)-a(11) from Donovan Johnson, Feb 18 2009
STATUS
approved