A066560 Smallest composite number divisible by n.

4, 4, 6, 4, 10, 6, 14, 8, 9, 10, 22, 12, 26, 14, 15, 16, 34, 18, 38, 20, 21, 22, 46, 24, 25, 26, 27, 28, 58, 30, 62, 32, 33, 34, 35, 36, 74, 38, 39, 40, 82, 42, 86, 44, 45, 46, 94, 48, 49, 50, 51, 52, 106, 54, 55, 56, 57, 58, 118, 60, 122, 62, 63, 64, 65, 66, 134, 68, 69, 70

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Formula

For n>=2: a(n) = 2*n if n prime; otherwise a(n) = n.

Prog

(PARI) a(n) = { if(n==1, 4, if(isprime(n), 2*n, n)) } \\ Harry J. Smith, Mar 02 2010

Crossrefs

Sequence in context: A131089 A256486 A204068 * A205031 A339719 A276683

Adjacent sequences: A066557 A066558 A066559 * A066561 A066562 A066563

Keyword

nonn

Author

Amarnath Murthy, Dec 17 2001

Extensions

More terms and formula from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 24 2001

Status

approved