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A208570
LCM of n and smallest nondivisor of n.
2
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
1,1
COMMENTS
a(n) = 2*n for all odd numbers.
LINKS
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)
EXAMPLE
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.
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 *)
PROG
(Haskell)
a208570 n = lcm n $ a007978 n -- Reinhard Zumkeller, May 22 2015
(PARI) a(n) = {my(k=2); while(!(n % k), k++); lcm(n, k); } \\ Michel Marcus, Mar 13 2018
CROSSREFS
Cf. A007978.
Cf. A258115.
Sequence in context: A306925 A134466 A062562 * A106832 A129902 A350631
KEYWORD
nonn
AUTHOR
J. Lowell, Feb 28 2012
EXTENSIONS
More terms from Alois P. Heinz, Mar 13 2012
STATUS
approved