login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A140761 Primes p(j) = A000040(j), j>=1, such that p(1)*p(2)*...*p(j) is an integral multiple of p(1)+p(2)+...+p(j). 6

%I #12 Nov 02 2020 20:38:54

%S 2,5,19,41,83,163,167,179,191,223,229,241,263,269,271,317,337,349,367,

%T 389,433,463,491,521,701,719,757,809,823,829,859,877,883,919,941,971,

%U 991,997,1021,1033,1049,1091,1153,1181,1193,1223,1291,1301,1319,1327,1361

%N Primes p(j) = A000040(j), j>=1, such that p(1)*p(2)*...*p(j) is an integral multiple of p(1)+p(2)+...+p(j).

%H Amiram Eldar, <a href="/A140761/b140761.txt">Table of n, a(n) for n = 1..10000</a>

%F Find integral quotients of products of consecutive primes divided by their sum.

%F a(n) = A000040(A051838(n)). - _R. J. Mathar_, Jun 09 2008

%e a(2) = 5 because it is the last consecutive prime in the run 2*3*5 = 30 and 2+3+5 = 10; since 30/10 = 3, it is the first integral quotient.

%t seq = {}; sum = 0; prod = 1; p = 1; Do[p = NextPrime[p]; prod *= p; sum += p; If[Divisible[prod, sum], AppendTo[seq, p]], {200}]; seq (* _Amiram Eldar_, Nov 02 2020 *)

%Y Cf. A002110, A007504, A051838, A116536, A140763, A159578.

%K easy,nonn

%O 1,1

%A _Enoch Haga_, May 28 2008

%E Edited by _R. J. Mathar_, Jun 09 2008

%E a(1) added by _Amiram Eldar_, Nov 02 2020

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 13 13:25 EDT 2024. Contains 375142 sequences. (Running on oeis4.)