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

1,1

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.

Links

Table of n, a(n) for n=1..88.

Prog

(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];

Crossrefs

Sequence in context: A321304 A361361 A280511 * A063960 A295514 A025510

Adjacent sequences: A200994 A200995 A200996 * A200998 A200999 A201000

Keyword

nonn

Author

Benoit Cloitre, Jan 08 2013

Status

approved