login
Smallest prime divisor of n-th primorial + (n+1)-st prime.
5

%I #29 Jun 17 2024 15:56:08

%S 5,11,37,13,23,30047,510529,9699713,127,107,433,1093,375569,

%T 13082761331670077,941879,32589158477190044789,1922760350154212639131,

%U 4129,92388407,5879,40729680599249024150621323549,1783,4903,10279098043,191,131,109,163,337,20261,673327,6599,181

%N Smallest prime divisor of n-th primorial + (n+1)-st prime.

%H Tyler Busby, <a href="/A065315/b065315.txt">Table of n, a(n) for n = 1..84</a> (terms 1..79 from Sean A. Irvine)

%H Romeo Mestrovic, <a href="http://arxiv.org/abs/1202.3670">Euclid's theorem on the infinitude of primes: a historical survey of its proofs (300 BC--2012) and another new proof</a>, arXiv preprint arXiv:1202.3670, 2012-2023. - From N. J. A. Sloane, Jun 13 2012

%F a(n) = A020639(A002110(n) + A000040(n+1)).

%F a(n) = A020639(A060881(n)). - _Michel Marcus_, Sep 08 2023

%e For n=3, 3rd primorial=30, prime(4)=7, sum=37, so a(3)=37.

%o (PARI) a(n) = vecmin(factor(prod(i=1, n, prime(i)) + prime(n+1))[,1]); \\ _Michel Marcus_, Aug 29 2019

%Y Cf. A002110, A000040, A006530, A057713, A002584, A002585, A051342, A060881.

%Y See also A065314, A065316, A065317.

%K nonn

%O 1,1

%A _Labos Elemer_, Oct 29 2001

%E More terms from _Michel Marcus_, Aug 29 2019