A093864 Consider the least k such that prime(k) > n*composite(k). Sequence gives prime(k).

11, 53, 173, 521, 1523, 4327, 11579, 31469, 85411, 229547, 614477, 1640461, 4393369, 11806297, 31656553, 84979847, 228346229, 614582509, 1654328267, 4457160931, 12016414601, 32419200013, 87508870037, 236325429049, 638490906857, 1725782162981, 4666340800001

Offset

1,1

Comments

a(n) = prime(A073459(n)).

Links

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

Example

a(2) = 53 as 53 > 2*26 where 53 and 26 are respectively the 16th prime and composite numbers.

Prog

(PARI) nextcomposite(k)=if(k<3, 4, if(isprime(k), k+1, k));
(PARI) p=2; q=4; for(n=1, 19, while(p<=n*q, p=nextprime(p+1); q=nextcomposite(q+1)); print1(p, ", "));

Crossrefs

Cf. A002808, A000040, A073459, A125075.

Sequence in context: A141893 A093198 A207361 * A139967 A227965 A196468

Adjacent sequences: A093861 A093862 A093863 * A093865 A093866 A093867

Keyword

nonn

Author

Amarnath Murthy, Apr 19 2004

Extensions

Terms a(4) to a(19) and PARI code from Klaus Brockhaus, Apr 26 2004

Terms a(20) to a(23) from Klaus Brockhaus, Nov 19 2006

More terms from David Wasserman, Apr 20 2007

Status

approved