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

1,1

Links

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

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 *)

Prog

(PARI) isA339912(n) = ((n>1)&&((2*bigomega(n))<bigomega(n-1)));

Crossrefs

Cf. A001222.

Subsequence of A339911 and of A339910.

Cf. also A339908.

Sequence in context: A105878 A054476 A319504 * A099184 A098095 A249953

Adjacent sequences: A339909 A339910 A339911 * A339913 A339914 A339915

Keyword

nonn

Author

Antti Karttunen, Dec 22 2020

Status

approved