A339912 Numbers k > 1 for which bigomega(k) < bigomega(k-1)/2, where bigomega gives the number of prime factors, counted with multiplicity.

13, 17, 19, 29, 31, 33, 37, 41, 43, 49, 53, 61, 65, 67, 71, 73, 79, 89, 97, 101, 103, 109, 113, 121, 127, 129, 131, 137, 139, 145, 149, 151, 157, 161, 163, 169, 173, 177, 181, 191, 193, 197, 199, 201, 209, 211, 217, 223, 229, 233, 239, 241, 251, 253, 257, 265, 269, 271, 277, 281, 283, 289, 293, 301, 305, 307, 311, 313

Offset: 1

Author

Antti Karttunen, Dec 22 2020

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..12313; all terms <= 65537

Crossrefs

Cf. A001222.

Subsequence of A339911 and of A339910.

Cf. also A339908.

Programs

Mathematica

Select[Range[3, 313, 2], PrimeOmega[#] < PrimeOmega[# - 1]/2 &] (* Michael De Vlieger, Dec 22 2020 *)
Flatten[Position[Partition[PrimeOmega[Range[400]],2,1],?(#[[2]]<#[[1]]/2&),1,Heads->False]]+1 (* _Harvey P. Dale, Jan 11 2024 *)

PARI

isA339912(n) = ((n>1)&&((2*bigomega(n))