0 together with numbers k such that 8*R_k - 7 is a prime, where R_k = 11...1 is the repunit (A002275) of length k.

A099421

0 together with numbers k such that 8*R_k - 7 is a prime, where R_k = 11...1 is the repunit (A002275) of length k.

Terms

    a(0) =0a(1) =3a(2) =19a(3) =79a(4) =139a(5) =223a(6) =463a(7) =544a(8) =1096a(9) =1419a(10) =3247a(11) =3877a(12) =4417a(13) =9507a(14) =11091a(15) =14602a(16) =27811a(17) =29188a(18) =106729a(19) =188308

External references