A339910 After 1, numbers k > 1 such that k has fewer prime divisors than k-1, when they are counted with multiplicity.

1, 5, 7, 9, 11, 13, 17, 19, 21, 23, 25, 29, 31, 33, 37, 41, 43, 46, 47, 49, 51, 53, 55, 57, 59, 61, 65, 67, 69, 71, 73, 77, 79, 81, 82, 83, 85, 89, 91, 93, 97, 101, 103, 105, 106, 107, 109, 111, 113, 115, 118, 121, 127, 129, 131, 133, 137, 139, 141, 145, 149, 151, 153, 155, 157, 161, 163, 166, 167, 169, 173, 177, 179

Offset: 1

Author

Antti Karttunen, Dec 22 2020

Keywords

• nonn

Comments

List of starts of nondecreasing runs of values of A001222 (= bigomega, number of prime factors, when counted with multiplicity).

Differs from A303578 (a similar sequence computed for tau, the number of divisors) for the first time at n=44, where a(44) = 105, a term missing from A303578.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..28208; all terms <= 65537

Crossrefs

Cf. A001222.

One more than A322839.

Cf. A339911, A339912 for subsequences.

Cf. also A303578.

Programs

Mathematica

1 + {0}~Join~Position[Sign@ Differences[Array[PrimeOmega, 180]], -1][[All, 1]] (* Michael De Vlieger, Dec 22 2020 *)

PARI

isA339910(n) = ((1==n)||(bigomega(n)