OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
A073484(a(n)) = 3.
EXAMPLE
1870 is a term, as 1870 = 2*5*11*17 = with three gaps: between 2 and 5, between 5 and 11 and between 11 and 17.
MATHEMATICA
q[n_] := SequenceCount[FactorInteger[n][[;; , 1]], {p1_, p2_} /; p2 != NextPrime[p1], Overlaps -> True] == 3; Select[Range[7500], SquareFreeQ[#] && q[#] &] (* Amiram Eldar, Apr 10 2021 *)
sfQ[n_]:=SquareFreeQ[n]&&Total[Boole[NextPrime[#[[1]]]!=#[[2]]&/@ Partition[ FactorInteger[n][[All, 1]], 2, 1]]]==3; Select[Range[7500], sfQ] (* Harvey P. Dale, Aug 29 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Aug 03 2002
STATUS
approved