Numbers k such that 4*10^k + 6*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

A099017

Numbers k such that 4*10^k + 6*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

Terms

    a(0) =0a(1) =1a(2) =2a(3) =6a(4) =10a(5) =12a(6) =13a(7) =22a(8) =32a(9) =46a(10) =61a(11) =68a(12) =90a(13) =110a(14) =652a(15) =1608a(16) =1904a(17) =2003a(18) =3038a(19) =3086a(20) =9580a(21) =9698a(22) =10639a(23) =14461

External references