A084309 a(n) = gcd(prime(n)-1, n).

1, 2, 1, 2, 5, 6, 1, 2, 1, 2, 1, 12, 1, 14, 1, 4, 1, 6, 1, 10, 3, 2, 1, 8, 1, 2, 3, 2, 1, 2, 1, 2, 1, 2, 1, 6, 1, 2, 1, 4, 1, 6, 1, 4, 1, 2, 1, 6, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 20, 1, 2, 9, 2, 13, 2, 1, 4, 1, 2, 1, 2, 1, 2, 3, 2, 1, 6, 1, 8, 1, 2, 1, 12, 1, 2, 1, 8, 1, 6, 1, 2, 3, 2, 1, 2, 1, 2, 9, 20, 1, 2

Offset

1,2

Links

Ivan Neretin, Table of n, a(n) for n = 1..10000

Maple

A084309:=n->gcd(ithprime(n)-1, n): seq(A084309(n), n=1..150); # Wesley Ivan Hurt, Feb 01 2017

Mathematica

Table[GCD[Prime[w]-1, w], {w, 128}]

Prog

(PARI) a(n) = gcd(prime(n)-1, n); \\ Michel Marcus, Feb 02 2017

Crossrefs

Cf. A084310, A084311, A084312, A084313, A084314, A084315, A084316.

Sequence in context: A111934 A098509 A019910 * A047991 A296666 A120898

Adjacent sequences: A084306 A084307 A084308 * A084310 A084311 A084312

Keyword

nonn,easy

Author

Labos Elemer, Jun 13 2003

Status

approved