Numbers k such that Sum_{x=2..k} (x-1)*3^(x-2) = ((2*k-3)*3^(k-1)+1)/4 is prime.
A125567
Numbers k such that Sum_{x=2..k} (x-1)*3^(x-2) = ((2*k-3)*3^(k-1)+1)/4 is prime.
Terms
- a(0) =3a(1) =6a(2) =10a(3) =135a(4) =186a(5) =542a(6) =1162a(7) =1726a(8) =4179a(9) =13910a(10) =14514a(11) =78915a(12) =170026
External references
- oeis: A125567