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

1,1

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

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 *)

Prog

(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

Crossrefs

Cf. A005101, A007686, A007707, A007741.

Sequence in context: A118646 A097969 A082280 * A146609 A121129 A051402

Adjacent sequences: A007705 A007706 A007707 * A007709 A007710 A007711

Keyword

nonn

Author

Walter Nissen

Extensions

More terms from Don Reble, Nov 10 2005

Status

approved