A238161 Greatest common divisor of the prime factors of n, each increased by 1

3, 4, 3, 6, 1, 8, 3, 4, 3, 12, 1, 14, 1, 2, 3, 18, 1, 20, 3, 4, 3, 24, 1, 6, 1, 4, 1, 30, 1, 32, 3, 4, 3, 2, 1, 38, 1, 2, 3, 42, 1, 44, 3, 2, 3, 48, 1, 8, 3, 2, 1, 54, 1, 6, 1, 4, 3, 60, 1, 62, 1, 4, 3, 2, 1, 68, 3, 4, 1, 72, 1, 74, 1, 2, 1, 4, 1, 80, 3, 4, 3, 84, 1, 6, 1, 2, 3, 90, 1, 2, 3, 4, 3, 2, 1, 98, 1, 4, 3

Offset

2,1

Links

Table of n, a(n) for n=2..100.

Example

10 has prime factors 2 and 5, which become 3 and 6 when respectively increased by 1, and gcd(3, 6) = 3. Therefore, a(10) = 3.

Mathematica

Table[Apply[GCD, (Transpose[FactorInteger[n]][[1]] + 1)], {n, 2, 100}]

Crossrefs

Sequence in context: A262150 A325594 A104076 * A332880 A281626 A327650

Adjacent sequences: A238158 A238159 A238160 * A238162 A238163 A238164

Keyword

nonn,easy

Author

Joseph L. Pe, Feb 18 2014

Status

approved