A091377 Numbers having fewer prime factors than the value of their smallest prime factor.

1, 2, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 29, 31, 33, 35, 37, 39, 41, 43, 47, 49, 51, 53, 55, 57, 59, 61, 65, 67, 69, 71, 73, 77, 79, 83, 85, 87, 89, 91, 93, 95, 97, 101, 103, 107, 109, 111, 113, 115, 119, 121, 123, 125, 127, 129, 131, 133, 137, 139, 141, 143

Offset

1,2

Comments

A091371(a(n)) > 0: A001222(a(n)) < A020639(a(n)).

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Mathematica

Select[Range[143], PrimeOmega[#]<FactorInteger[#][[1, 1]]&] (* James C. McMahon, Dec 28 2024 *)

Prog

(PARI) is(n)=if(n%2==0, return(n==2)); if(n<27, return(1)); forprime(p=2, bigomega(n), if(n%p==0, return(0))); 1 \\ Charles R Greathouse IV, Sep 14 2015

Crossrefs

Cf. A091374, A091376, A091375.

Sequence in context: A004280 A053224 A277334 * A336119 A213511 A092919

Adjacent sequences: A091374 A091375 A091376 * A091378 A091379 A091380

Keyword

nonn,easy

Author

Reinhard Zumkeller, Jan 04 2004

Status

approved