A090926 Least odd prime divisor of prime(n)-1, or a(n) = 2 if no odd prime divisors are encountered.

2, 2, 3, 5, 3, 2, 3, 11, 7, 3, 3, 5, 3, 23, 13, 29, 3, 3, 5, 3, 3, 41, 11, 3, 5, 3, 53, 3, 7, 3, 5, 17, 3, 37, 3, 3, 3, 83, 43, 89, 3, 5, 3, 7, 3, 3, 3, 113, 3, 29, 7, 3, 5, 2, 131, 67, 3, 3, 5, 3, 73, 3, 5, 3, 79, 3, 3, 173, 3, 11, 179, 3, 3, 3, 191, 97, 3, 5, 3, 11, 3, 5, 3, 3, 13

Offset

2,1

Links

Table of n, a(n) for n=2..86.

Example

a(8) = 2 as prime(8) = 17 and 17-1 = 2^4.
a(10) = 7 as prime(10) = 29 and 29-1 =28 = 2*7^2.

Crossrefs

Sequence in context: A185688 A203955 A039638 * A023503 A241195 A039640

Adjacent sequences: A090923 A090924 A090925 * A090927 A090928 A090929

Keyword

base,easy,nonn

Author

Amarnath Murthy, Dec 26 2003

Extensions

More terms from Erich Friedman, Aug 08 2005

Status

approved