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Smallest sum of n consecutive odd primes which is a multiple of n.
5

%I #15 Jan 17 2023 16:34:15

%S 3,8,15,36,395,72,119,240,2349,300,539,276,923,714,435,496,629,702,

%T 2375,1120,1995,1144,3979,3192,3925,2938,9531,1960,10063,2670,3441,

%U 4448,5907,6358,9835,4464,5069,3610,13533,4000,6273,4410,21113,12012,8325,8142

%N Smallest sum of n consecutive odd primes which is a multiple of n.

%H Zak Seidov, <a href="/A132810/b132810.txt">Table of n, a(n) for n = 1..1000</a>

%F Let A132809(n)=prime(i). Then a(n)= sum(j=i...i+n-1) prime(j). - _R. J. Mathar_, Nov 27 2007

%e a(5)=395, associated with A132809(5)=71=prime(20) as the first of the 5 consecutive primes, is the smallest sum of 5 consecutive odd primes which is divisible by n=5.

%t Table[Module[{nn=n,ncop},ncop=Total/@Partition[Prime[Range[2,2500]],nn,1];SelectFirst[ ncop,Mod[#,nn]==0&]],{n,50}] (* _Harvey P. Dale_, Jan 17 2023 *)

%Y Cf. A132809, A132811.

%K easy,nonn

%O 1,1

%A _Enoch Haga_, Sep 01 2007

%E The example does not match the sequence. Also the offset for all of this bunch of sequences should probably be 1. - _N. J. A. Sloane_, Sep 13 2007

%E Edited by _R. J. Mathar_, Nov 27 2007