A076986 - OEIS

A076986

Smallest squarefree number of the form n*k + 1.

2, 3, 7, 5, 6, 7, 15, 17, 10, 11, 23, 13, 14, 15, 31, 17, 35, 19, 39, 21, 22, 23, 47, 73, 26, 53, 55, 29, 30, 31, 94, 33, 34, 35, 71, 37, 38, 39, 79, 41, 42, 43, 87, 89, 46, 47, 95, 97, 197, 51, 103, 53, 107, 55, 111, 57, 58, 59, 119, 61, 62, 187, 127, 65, 66

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..1000

EXAMPLE

a(24) = 73 as 25 and 49 are not squarefree.

PROG

(PARI) a(n)={my(k=1); while(!issquarefree(n*k+1), k++); n*k+1} \\ Andrew Howroyd, Jan 16 2020

CROSSREFS

Cf. A005117 (squarefree numbers).

Sequence in context: A069771 A330423 A235801 * A333386 A357579 A334126