A114797 - OEIS

A114797

a(n) = n multiplied by the least nontrivial nondivisor of n.

6, 12, 10, 24, 14, 24, 18, 30, 22, 60, 26, 42, 30, 48, 34, 72, 38, 60, 42, 66, 46, 120, 50, 78, 54, 84, 58, 120, 62, 96, 66, 102, 70, 180, 74, 114, 78, 120, 82, 168, 86, 132, 90, 138, 94, 240, 98, 150, 102, 156, 106, 216, 110, 168, 114, 174, 118, 420, 122, 186, 126, 192

(list; graph; refs; listen; history; text; internal format)

OFFSET

3,1

COMMENTS

a(2n-1) = 4n-2. a(n!) = p*n! where p is the least prime > n, because all the number from n+1, n+2 up to p-1 would divide n!.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 3..1000

EXAMPLE

a(24) = 24*5 = 120 as 2,3,4 divide 24.

MATHEMATICA

Do[l = Range[1, n]; m = Divisors[n]; s = Complement[l, m]; Print[n * Min[s]], {n, 3, 100}] (* Ryan Propper, Jul 21 2006 *)

# First[Complement[Range[#], Divisors[#]]]&/@Range[3, 70] (* Harvey P. Dale, Dec 27 2012 *)