A034847 a(n) = 1 + 4*A034780(n).

29, 53, 101, 109, 149, 173, 181, 197, 229, 269, 293, 317, 337, 349, 373, 389, 461, 509, 557, 569, 641, 653, 677, 701, 709, 773, 797, 821, 829, 853, 937, 941, 1013, 1021, 1033, 1061, 1069, 1109, 1117, 1181, 1193, 1217, 1229, 1277, 1297, 1301, 1373, 1429, 1481, 1493, 1549, 1597

Offset: 1

Author

Labos Elemer

Keywords

• nonn

Comments

a(n) = P(n,4) = 1 + 4*K(n,4) = 1 + 4*A034780(n). P(n,4) are special primes of the form 4k+1. The relevant values of k are given by A034780.

Note that, e.g., 5 and 13 are not in this sequence.

Crossrefs

Cf. A034693, A034694, A034780.

Programs

PARI

a034693(n) = my(s=1); while(!isprime(s*n+1), s++); s;
isok(n) = a034693(n) == 4;
lista(nn) = {for (n=1, nn, if (isok(n), print1(4*n+1, ", ")););} \\ Michel Marcus, May 13 2018

Extensions

More terms from Michel Marcus, May 13 2018