A214069 Least m>0 such that prime(n)+m and n-m are relatively prime.

2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 6, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 4, 2, 4, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 6, 1, 2, 1, 2, 2, 6, 1, 2, 2, 2, 1, 4, 1, 2, 1, 2, 2, 4, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 4, 1, 2, 1, 2

Offset

1,1

Links

Clark Kimberling, Table of n, a(n) for n = 1..1000

Example

gcd(12,10) = 2 and gcd(13,9) = 1, so that a(11) = 2.

Mathematica

Table[m = 1; While[GCD[Prime[n] + m, n - m] != 1, m++]; m, {n, 1, 140}]

Prog

(PARI) vector(100, n, m=1; while(gcd(prime(n)+m, n-m)!=1, m++); m) \\ Derek Orr, May 30 2015

Crossrefs

Cf. A214052.

Sequence in context: A161058 A161262 A161287 * A167969 A245192 A235431

Adjacent sequences: A214066 A214067 A214068 * A214070 A214071 A214072

Keyword

nonn,easy

Author

Clark Kimberling, Jul 26 2012

Status

approved