A082287 - OEIS

%I #15 Jan 08 2020 16:24:07

%S 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,

%T 20,21,21,22,22,23,24,24,25,26,26,27,28,28,29,30,30,30,31,32,33,33,34,

%U 34,35,35,36,36,37,38,38,39,39,40,40,41,42,42,42,43,44,44,45,45,46,46,47

%N 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.

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

%H Harvey P. Dale, <a href="/A082287/b082287.txt">Table of n, a(n) for n = 1..1000</a>

%F 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

%t Join[{1},Flatten[Table[PadRight[{},PrimeNu[n],n],{n,2,50}]]] (* _Harvey P. Dale_, Jan 08 2020 *)

%o (PARI) a(n)=if(n<0,0,t=1;while(sum(k=1,t,floor(t/prime(k)))<n,t++);t) \\ _Benoit Cloitre_, Nov 08 2009

%Y Cf. A082288.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Apr 07 2003