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A074173
Numbers n such that n and n+2 are of the form p^2*q where p and q are distinct primes.
5
18, 50, 242, 423, 475, 603, 637, 722, 845, 925, 1682, 1773, 2007, 2523, 2525, 2527, 3175, 3177, 4203, 4475, 4525, 4923, 5823, 6725, 6811, 6962, 7299, 7442, 7675, 8425, 8957, 8973, 9457, 9925, 10051, 10082, 10467, 11673, 11709, 12427, 12482, 12591
OFFSET
1,1
FORMULA
Even terms in sequence are 2*A048161(n)^2. - Ray Chandler, Jun 24 2019
EXAMPLE
18 is a member as 18 = 3^2*2 and 20 = 2^2*5.
MATHEMATICA
lst={}; Do[f1=FactorInteger[n]; If[Sort[Transpose[f1][[2]]]=={1, 2}, f2=FactorInteger[n+2]; If[Sort[Transpose[f2][[2]]]=={1, 2}, AppendTo[lst, n]]], {n, 3, 10000}]; lst
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Aug 30 2002
EXTENSIONS
More terms from T. D. Noe, Oct 04 2004
STATUS
approved