A175154 a(n) = prime index of A048059(n).

5, 6, 7, 9, 11, 13, 16, 19, 23, 26, 39, 44, 54, 61, 66, 71, 83, 103, 121, 143, 152, 160, 197, 238, 248, 270, 313, 336, 386, 403, 453, 481, 512, 527, 542, 619, 635, 714, 752, 804, 842, 857, 898, 915, 933, 1092, 1112, 1154, 1242, 1265, 1307, 1372, 1412, 1534, 1561

Offset

1,1

Comments

Indices of primes of the form n^2+n+11.

PrimePi(A048059(n)), where PrimePi(k) is the number of primes <= k (A000720).

prime(a(n)) = A048059(n).

Links

Table of n, a(n) for n=1..55.

Formula

a(n) = A000720(A048059(n)).

Example

A048059(7) = 53 is the seventh prime of the form n^2+n+11; 53 has prime index 16 (PrimePi(53) = 16, prime(16) = 53). Hence a(7) = 16.

Prog

(Magma) PrimePi:=func< n | #PrimesUpTo(n) >; [ PrimePi(p): x in [0..120] | IsPrime(p) where p is x^2+x+11 ];

Crossrefs

Cf. A048058 (n^2+n+11), A048097 (n such that n^2+n+11 is prime), A048059 (primes of the form n^2+n+11), A000720 (PrimePi(n), number of primes <= n), A173752.

Sequence in context: A180061 A196029 A096820 * A355239 A030388 A031059

Adjacent sequences: A175151 A175152 A175153 * A175155 A175156 A175157

Keyword

nonn

Author

Klaus Brockhaus, Feb 27 2010

Status

approved