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

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

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

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

Mathematica

a[n_]:=Module[{k=1}, While[!Divisible[2n-1, k] || k<Sqrt[2n-1] , k++]; k]; Array[a, 67] (* Stefano Spezia, Nov 17 2024 *)
Table[Select[Divisors[2n-1], #>=Sqrt[2n-1]&][[1]], {n, 70}] (* Harvey P. Dale, Jun 09 2026 *)

Crossrefs

Odd bisection of A033677.

Cf. A377499, A219695.

Sequence in context: A088836 A076565 A286517 * A199423 A100029 A099984

Adjacent sequences: A377862 A377863 A377864 * A377866 A377867 A377868

Keyword

nonn,easy

Author

Charles Kusniec, Nov 10 2024

Status

approved