A208570 LCM of n and smallest nondivisor of n.
2, 6, 6, 12, 10, 12, 14, 24, 18, 30, 22, 60, 26, 42, 30, 48, 34, 36, 38, 60, 42, 66, 46, 120, 50, 78, 54, 84, 58, 60, 62, 96, 66, 102, 70, 180, 74, 114, 78, 120, 82, 84, 86, 132, 90, 138, 94, 240, 98, 150, 102, 156, 106, 108, 110, 168, 114, 174, 118, 420, 122
Offset: 1
Keywords
Examples
a(6) = 12 because the divisors of 6 are 1,2,3,6; 4 is the smallest number not a divisor of 6; the LCM of 6 and 4 is 12.
Links
- Alois P. Heinz, Table of n, a(n) for n = 1..10000
Programs
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Haskell
a208570 n = lcm n $ a007978 n -- Reinhard Zumkeller, May 22 2015
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Maple
a:= proc(n) local t; for t from 2 do if irem (n, t)<>0 then return ilcm(t, n) fi od end: seq(a(n), n=1..100); # Alois P. Heinz, Mar 13 2012 -
Mathematica
Table[LCM[n, Min[Complement[Range[n + 1], Divisors[n]]]], {n, 61}] (* Ivan Neretin, May 20 2015 *) -
PARI
a(n) = {my(k=2); while(!(n % k), k++); lcm(n, k); } \\ Michel Marcus, Mar 13 2018
Formula
From Robert Israel, May 20 2015: (Start)
a(n) = lcm(n, A007978(n)).
For primes p let nu_p(n) be the p-adic order of n.
a(n) = p * n where p is the prime that minimizes p^(1+nu_p(n)). (End)
Extensions
More terms from Alois P. Heinz, Mar 13 2012
Comments