A377865 Smallest divisor of 2n-1 greater than or equal to sqrt(2n-1).

1, 3, 5, 7, 3, 11, 13, 5, 17, 19, 7, 23, 5, 9, 29, 31, 11, 7, 37, 13, 41, 43, 9, 47, 7, 17, 53, 11, 19, 59, 61, 9, 13, 67, 23, 71, 73, 15, 11, 79, 9, 83, 17, 29, 89, 13, 31, 19, 97, 11, 101, 103, 15, 107, 109, 37, 113, 23, 13, 17, 11, 41, 25, 127, 43, 131, 19

Offset: 1

Author

Charles Kusniec, Nov 10 2024

Keywords

• nonn
• easy

Crossrefs

Odd bisection of A033677.

Cf. A377499, A219695.

Programs

Mathematica

a[n_]:=Module[{k=1},While[!Divisible[2n-1,k] || kStefano Spezia, Nov 17 2024 *)

Formula

a(n) = A033677(2n-1).

a(n) = A377499(n) + A219695(n).