A234387 a(n) = n-th smallest prime congruent to 1 modulo prime(n).

3, 13, 41, 113, 331, 443, 613, 1103, 1013, 1741, 2543, 3257, 3691, 4129, 4889, 6997, 6491, 8053, 8443, 12071, 11681, 12799, 15439, 18869, 20759, 21211, 20807, 27179, 33791, 28703, 37339, 39301, 37813, 53377, 51853, 54059, 62801, 60637, 74149, 72661, 77687, 62989, 81749, 79903, 79589, 109849, 102547

Offset: 1

Author

Zak Seidov, Dec 25 2013

Keywords

• nonn

Examples

			a(3) = 41 because prime(3) = 5 and primes == 1 mod 5 are 11, 31, 41;
a(4) = 113 because prime(4) = 7 and primes == 1 mod 7 are 29, 43, 71, 113.
		

Links

• Zak Seidov and Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 1000 terms from Seidov)

Crossrefs

Cf. A035095, A234372.

Programs

Mathematica

Reap[Sow[3];Do[c=0;q=Prime[n];p=1;While[c
				

PARI

a(n)=if(n<2,return(3)); my(p=prime(n),q=2*p+1); while(n, if(isprime(q), n--); q+= 2*p); q-2*p \\ Charles R Greathouse IV, Dec 26 2013