A049537 Values of k for which A075059(k) = A003418(k) + 1 is prime.

0, 1, 2, 3, 4, 5, 6, 7, 9, 10, 19, 20, 21, 22, 25, 26, 31, 47, 48, 89, 90, 91, 92, 93, 94, 95, 96, 127, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 1369, 1370, 1371, 1372, 2251, 2252, 2253, 2254, 2255, 2256, 2257, 2258, 2259, 2260, 2261, 2262, 2263, 2264, 2265, 2266, 3271, 3272, 3273, 3274, 3275, 3276, 3277, 3278, 3279, 3280, 3281, 3282, 3283, 3284, 3285, 3286, 3287

Offset: 1

Author

Labos Elemer

Keywords

• nonn

Examples

			8 is not in the sequence because A075059(8) = 1 + A003418(8) = 1 + lcm(1, 2, ..., 8) = 841 = 29^2 is not prime.
127 is in the sequence because A075059(127) = 1 + A003418(127) = 1 + lcm(1, 2, ..., 127) = 6676878045498705789701874602220118271269436344024536001 is prime.
		

Links

• Jinyuan Wang, Table of n, a(n) for n = 1..150

Crossrefs

Cf. A000040, A003418, A049536, A057825, A075059.

Programs

Mathematica

Join[{0}, Select[Range[250], PrimeQ[LCM@@Range[#]+1]&]] (* Harvey P. Dale, Nov 15 2011 *)

PARI

isok(n) = isprime(lcm(vector(n, i, i))+1); \\ Michel Marcus, Feb 25 2014

Extensions

a(43)-a(57) from Ray Chandler, Jan 16 2009

a(1)=0 prepended and a(58)-a(86) added by Max Alekseyev, Sep 04 2015