A049537 - OEIS

%I #21 May 02 2020 09:49:23

%S 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,

%T 96,127,139,140,141,142,143,144,145,146,147,148,1369,1370,1371,1372,

%U 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

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

%H Jinyuan Wang, <a href="/A049537/b049537.txt">Table of n, a(n) for n = 1..150</a>

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

%e 127 is in the sequence because A075059(127) = 1 + A003418(127) = 1 + lcm(1, 2, ..., 127) = 6676878045498705789701874602220118271269436344024536001 is prime.

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

%o (PARI) isok(n) = isprime(lcm(vector(n, i, i))+1); \\ _Michel Marcus_, Feb 25 2014

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

%K nonn

%O 1,3

%A _Labos Elemer_

%E a(43)-a(57) from _Ray Chandler_, Jan 16 2009

%E a(1)=0 prepended and a(58)-a(86) added by _Max Alekseyev_, Sep 04 2015