A086545 Smallest k such that n*k+1 is a prime and (n-1)/k is noncomposite, or 0 if no such number exists.

1, 2, 1, 2, 1, 6, 0, 4, 3, 2, 1, 4, 0, 2, 15, 8, 1, 0, 0, 10, 3, 2, 0, 24, 5, 0, 27, 0, 1, 10, 0, 0, 3, 2, 5, 0, 0, 2, 13, 20, 1, 0, 0, 4, 15, 0, 0, 0, 0, 50, 3, 0, 0, 18, 5, 8, 19, 0, 1, 12, 0, 2, 9, 32, 5, 66, 0, 4, 3, 0, 1, 24, 0, 2, 25, 38, 7, 78, 0, 16, 0, 2, 0, 12, 5, 0, 0, 44, 89, 30, 0, 4, 3, 2

Offset

2,2

Links

Table of n, a(n) for n=2..95.

Example

a(7) = 6 as 7*6 + 1 = 43 is a prime and (7 - 1)/6 = 1 is noncomposite.
a(10) = 3 as 10*3 + 1 = 31 and (10 - 1)/3 = 3 both are primes.

Crossrefs

Sequence in context: A217437 A152823 A324605 * A337395 A126083 A356158

Adjacent sequences: A086542 A086543 A086544 * A086546 A086547 A086548

Keyword

nonn

Author

Amarnath Murthy, Aug 26 2003

Extensions

Corrected and extended by David Wasserman, Mar 22 2005

Status

approved