1,1

Table of n, a(n) for n=1..27.

a(9) = 5039: lcm(1..9) = 2520; 2519 is not a prime but 2*2520 - 1 = 5039 is a prime.

(PARI) a(n) = {my(lcmn = lcm(vector(n, k, k)), k = 1); while(!isprime(p = k*lcmn-1), k++); p; } \\ Michel Marcus, Mar 15 2018

Cf. A070858.

Sequence in context: A000905 A065296 A114895 * A243755 A242334 A087524

Adjacent sequences: A083682 A083683 A083684 * A083686 A083687 A083688

nonn

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 15 2003

Corrected and extended by Vladeta Jovovic, Jun 16 2003

approved