A082287 a(1) = 1; for n > 1, n appears omega(n) times, where omega(n)=A001221(n) is the number of distinct prime factors of n, a(1)=1.

1, 2, 3, 4, 5, 6, 6, 7, 8, 9, 10, 10, 11, 12, 12, 13, 14, 14, 15, 15, 16, 17, 18, 18, 19, 20, 20, 21, 21, 22, 22, 23, 24, 24, 25, 26, 26, 27, 28, 28, 29, 30, 30, 30, 31, 32, 33, 33, 34, 34, 35, 35, 36, 36, 37, 38, 38, 39, 39, 40, 40, 41, 42, 42, 42, 43, 44, 44, 45, 45, 46, 46, 47

Offset: 1

Author

Reinhard Zumkeller, Apr 07 2003

Keywords

• nonn

Comments

A027748(n) divides a(n) and a(n)=A027748(n) iff a(n) is prime; a(A013939(n)+1)=n.

Links

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

Crossrefs

Cf. A082288.

Programs

Mathematica

Join[{1},Flatten[Table[PadRight[{},PrimeNu[n],n],{n,2,50}]]] (* Harvey P. Dale, Jan 08 2020 *)

PARI

a(n)=if(n<0,0,t=1;while(sum(k=1,t,floor(t/prime(k)))Benoit Cloitre, Nov 08 2009

Formula

a(n) is the least k such that Sum_{p<=k} floor(k/p) >= n where p runs through the primes. - Benoit Cloitre, Nov 08 2009