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

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

Adjacent sequences: A076983 A076984 A076985 * A076987 A076988 A076989

Keyword

easy,nonn

Author

Amarnath Murthy, Oct 25 2002

Extensions

a(26) corrected and a(27) and beyond from Andrew Howroyd, Jan 16 2020

Status

approved