A104294 a(n) = prime((prime(n)+1)/2).

3, 5, 7, 13, 17, 23, 29, 37, 47, 53, 67, 73, 79, 89, 103, 113, 127, 139, 151, 157, 173, 181, 197, 227, 233, 239, 251, 257, 269, 311, 317, 347, 349, 379, 383, 401, 421, 433, 449, 463, 467, 503, 509, 523, 541, 577, 613, 619, 631

Offset

2,1

Comments

n=1 is a degenerate case because prime(1)=2, (prime(n)+1)/2 = 3/2 and there is no prime(3/2).

Links

Table of n, a(n) for n=2..50.

Formula

a(n) = A104293(n+1).

a(n) = A104295(n) + A104293(n).

Example

a(5)=13 because prime((prime(5)+1)/2) = prime((11+1)/2) = prime(6) = 13;
a(7)=23 because prime((prime(7)+1)/2) = prime((17+1)/2) = prime(9) = 23.

Mathematica

Table[Prime[(Prime[n]+1)/2], {n, 2, 50}]

Prog

(PARI) vector(100, n, prime((prime(n+1)+1)/2)) \\ Derek Orr, Mar 29 2015

Crossrefs

Cf. A104293 (prime((prime(n)-1)/2)), A104295.

Sequence in context: A032397 A028879 A067567 * A372141 A262100 A171566

Adjacent sequences: A104291 A104292 A104293 * A104295 A104296 A104297

Keyword

easy,nonn

Author

Zak Seidov, Feb 28 2005

Status

approved