A076252 Integers k such that omega(k) = omega(k-1) + omega(k-2) + omega(k-3), where omega(n) is the number of distinct prime factors of n.

2310, 3990, 4290, 6090, 6270, 10010, 11550, 12810, 13650, 17094, 17940, 18270, 19380, 21930, 22110, 22770, 23100, 24990, 25410, 27300, 28644, 30090, 32214, 32604, 34034, 34314, 35340, 35880, 37310, 38190, 38570, 38640, 39270, 39780

Offset: 1

Author

Joseph L. Pe, Nov 04 2002

Keywords

• nonn

Examples

			omega(2310) = 5 = 1 + 2 + 2 = omega(2309) + omega(2308) + omega(2307), so 2310 belongs to the sequence.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A001221, A006049, A076251, A076253.

Programs

Mathematica

omega[n_] := Length[FactorInteger[n]]; a = {}; Do[If[omega[n] == omega[n - 1] + omega[n - 2] + omega[n - 3], a = Append[a, n]], {n, 1, 10^5}]; a
Flatten[Position[Partition[PrimeNu[Range[40000]],4,1],?(#[[4]] == Total[ Take[ #,3]]&), {1}, Heads->False]]+3 (* _Harvey P. Dale, Oct 31 2016 *)