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

1,1

Links

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

Example

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.

Mathematica

Reap[Sow[3]; Do[c=0; q=Prime[n]; p=1; While[c<n, p=p+2q; If[PrimeQ[p], c++]]; Sow[p], {n, 2, 100}]][[2, 1]]

Prog

(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

Crossrefs

Cf. A035095, A234372.

Sequence in context: A309139 A049167 A241527 * A173867 A121162 A146018

Adjacent sequences: A234384 A234385 A234386 * A234388 A234389 A234390

Keyword

nonn

Author

Zak Seidov, Dec 25 2013

Status

approved