A200997 Terms of A135506 sorted (after removing the 1's).

2, 2, 5, 5, 5, 5, 7, 11, 11, 11, 13, 13, 13, 13, 13, 13, 13, 13, 17, 17, 17, 19, 23, 23, 23, 23, 23, 29, 29, 29, 29, 29, 31, 37, 41, 41, 41, 43, 43, 43, 43, 43, 47, 47, 47, 47, 47, 53, 53, 53, 59, 59, 59, 59, 59, 61, 61, 61, 61, 61, 61, 61, 67, 67, 67, 67, 67, 71, 71, 71, 73, 73, 73, 73, 73, 73, 73, 73, 73, 73, 73, 73, 73, 79, 83, 83, 83, 89

Offset: 1

Author

Benoit Cloitre, Jan 08 2013

Keywords

• nonn

Comments

Terms of the sequence are primes and all primes except 3 appear finitely many times. p>=5 occurs 1 time iff 2p-1 is prime (cf. A005382). p>=11 occurs 3 times iff 4p-1 is prime (cf. A062737). In general p occurs 2m-1 times iff 2mp-1 is prime and 2ip-1 is composite for i=1,2,3,...,m-1.

Programs

PARI

v=[];u1=1;for(n=2,1000,u2=u1+lcm(n,u1);r=u1;u1=u2;if(u2/r-1>1,v=concat(v,[u2/r-1]);));w=vecsort(v);a(n)=w[n];