A007708 Prime(n)*...*a(n) is the least product of consecutive primes which is abundant.

5, 13, 31, 73, 149, 233, 367, 521, 733, 991, 1249, 1579, 1949, 2341, 2791, 3343, 3881, 4481, 5147, 5849, 6619, 7499, 8387, 9341, 10321, 11411, 12517, 13709, 15013, 16363, 17881, 19381, 20873, 22369, 24007, 25763, 27611, 29399, 31357

Offset: 1

Author

Walter Nissen

Keywords

• nonn

Comments

Differs from A007686 only for n=1. - Michel Marcus, Mar 10 2013

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A005101, A007686, A007707, A007741.

Programs

Mathematica

a[n_] := Module[{p = Prime[n]}, r = 1 + 1/p; While[r <= 2,  p = NextPrime[p]; r *= 1 + 1/p]; p]; Array[a, 39] (* Amiram Eldar, Jun 29 2019 *)

PARI

a(n) = {p = prime(n); sig = p+1; prd = p; while (sig <= 2*prd, p = nextprime(p+1); sig *= p+1; prd *= p;); return (p);} \\ Michel Marcus, Mar 10 2013

Extensions

More terms from Don Reble, Nov 10 2005