A103856 - OEIS

%I #17 Dec 30 2024 02:12:07

%S 1,1,7,4831,3673,16349,5240507,4159,83,3911,401,61,66935021479,199,73,

%T 152249,379,5014363,181,191,277,155893,35851,431,1499

%N Smallest prime factor of prime(n)! - prime(n)# + 1.

%C a(26) has 160 digits and is too large to be included here.

%H Amiram Eldar, <a href="/A103856/b103856.txt">Table of n, a(n) for n = 1..26</a>

%H Reinhard Zumkeller, <a href="/A103855/a103855.txt">p(n)! - p(n)# + 1</a>.

%F a(n) = A020639(A103855(n)).

%o (PARI) a(n) = if(n>2, factor(prime(n)!-factorback(primes(n))+1)[1, 1], 1); \\ _Jinyuan Wang_, Dec 30 2024

%Y Cf. A020639, A103855, A103857, A103891.

%K nonn

%O 1,3

%A _Reinhard Zumkeller_, Feb 20 2005