A103598 Smallest prime p such that Sum_{primes q <= p} 1/q >= n/5.

2, 2, 3, 3, 5, 11, 17, 41, 97, 277, 1013, 4789, 31627, 314723, 5195977, 159490147, 10443979657

Offset: 1

Author

James R. Buddenhagen, Mar 28 2005

Keywords

• nonn

Comments

a(18) > pi(5*10^10). - Robert Price, Dec 10 2013

Crossrefs

Cf. A016088, A046024, A103591-A103600.

Programs

Mathematica

For[n = 1, n ≤ 17, n++, sum = 0; For[k = 1, k ≤ 10^6, k++, sum = sum + 1/Prime[k]; If[sum >= n/5, Print[Prime[k]]; Break[]]]]
Table[m = 1; s = 0; While[(s = s + 1/Prime[m]) < n/5, m++];
Prime[m], {n, 1, 17}] (* Robert Price, Mar 27 2019 *)

Extensions

a(1)-a(2) and a(16)-a(17) from Robert Price, Dec 10 2013