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A007708 Prime(n)*...*a(n) is the least product of consecutive primes which is abundant. 9

%I

%S 5,13,31,73,149,233,367,521,733,991,1249,1579,1949,2341,2791,3343,

%T 3881,4481,5147,5849,6619,7499,8387,9341,10321,11411,12517,13709,

%U 15013,16363,17881,19381,20873,22369,24007,25763,27611,29399,31357

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

%C Differs from A007686 only for n=1. - _Michel Marcus_, Mar 10 2013

%H Amiram Eldar, <a href="/A007708/b007708.txt">Table of n, a(n) for n = 1..1000</a>

%t 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 *)

%o (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

%Y Cf. A005101, A007686, A007707, A007741.

%K nonn

%O 1,1

%A _Walter Nissen_

%E More terms from _Don Reble_, Nov 10 2005

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Last modified November 18 02:07 EST 2019. Contains 329242 sequences. (Running on oeis4.)