A082419 Numbers n such that P(n+2) < P(n) < P(n+1), where P(n) = largest prime factor of n (A006530).

6, 10, 22, 25, 28, 30, 33, 46, 52, 58, 68, 70, 78, 82, 88, 93, 98, 102, 106, 110, 115, 126, 130, 133, 138, 141, 145, 148, 160, 166, 172, 178, 187, 190, 198, 201, 205, 208, 213, 222, 226, 232, 236, 238, 248, 253, 262, 268, 273, 286, 292, 304, 306, 310, 316, 328, 346, 348

Offset: 1

Author

N. J. A. Sloane, Apr 25 2003

Keywords

• nonn

References

• Antal Balog, On the largest prime factor of consecutive integers, Abstracts Amer. Math. Soc., 25 (No. 2, 2002), p. 337, #975-11-76.

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000
• P. Erdős and C. Pomerance, On the largest prime factors of n and n+1, Aequationes Math. 17 (1978), p. 311-321. [alternate link]

Crossrefs

Cf. A006530, A082417-A082422, A071869, A071870.

Programs

Mathematica

pflist=Select[Partition[Table[{n,lpf[n]},{n,400}],3,1],#[[3,-1]]< #[[1,-1]]< #[[2,-1]]&]; Table[pflist[[n,1,1]],{n,Length[pflist]}] (* Harvey P. Dale, Oct 25 2011 *)