A271503 -id:A271503 - cp's OEIS frontend

A271504 With a(1) = 1, a(n) is the LCM of all 0 < m < n for which a(m) divides n.

1, 1, 2, 6, 2, 60, 2, 210, 2, 630, 2, 13860, 2, 90090, 2, 90090, 2, 3063060, 2, 29099070, 2, 29099070, 2, 1338557220, 2, 3346393050, 2, 10039179150, 2, 582272390700, 2, 9025222055850, 2, 9025222055850, 2, 18050444111700, 2, 333933216066450, 2, 333933216066450

Offset: 1

Peter Kagey, Apr 08 2016

nonn

Chai Wah Wu, Table of n, a(n) for n = 1..2309 (n = 1..100 from Peter Kagey)

Cf. A269347, A271503.

a = {1}; Do[AppendTo[a, LCM @@ Select[Range[n - 1], Divisible[n, a[[#]]] &]], {n, 2, 40}]; a (* Michael De Vlieger, Apr 08 2016 *)

a(2n + 1) = 2 for all n > 1.

a(n) is even for all n > 2.

A271774 a(1) = 1, then a(n) is the maximum of all 0 < m < n for which a(m) divides n.

Original entry on oeis.org

1, 1, 2, 3, 2, 5, 2, 7, 4, 7, 2, 11, 2, 13, 6, 13, 2, 17, 2, 19, 10, 19, 2, 23, 6, 23, 4, 27, 2, 29, 2, 31, 12, 31, 10, 33, 2, 37, 16, 37, 2, 41, 2, 43, 6, 43, 2, 47, 10, 49, 18, 47, 2, 53, 12, 53, 22, 53, 2, 59, 2, 61, 10, 61, 16, 61, 2, 67, 26, 67, 2, 71, 2

Offset: 1

Peter Kagey, Apr 14 2016

nonn

If n is an odd prime, then a(n) = 2 and a(n+1) = n. All n for which a(n) = 2 are odd primes. - Robert Israel, Apr 14 2016

			a(1) = 1 by definition.
a(2) = 1 because a(1) divides 2.
a(3) = 2 because a(2) divides 3.
a(4) = 3 because a(3) divides 4.
a(5) = 2 because a(2) divides 5.
a(6) = 5 because a(5) divides 6.
a(7) = 2 because a(2) divides 7.
a(8) = 7 because a(7) divides 8.

Robert Israel, Table of n, a(n) for n = 1..10000

Cf. A088167, A269347, A271503, A271504, A271773.

A:= proc(n) option remember; local m;
    for m from n-1 by -1 do
      if n mod A(m) = 0 then return m fi
    od
end proc:
A(1):= 1:
seq(A(i),i=1..100); # Robert Israel, Apr 14 2016

a[1] = 1; a[n_] := a[n] = Block[{m = n - 1}, While[Mod[n, a[m]] > 0, m--]; m]; Array[a, 100] (* Giovanni Resta, Apr 14 2016 *)

cp's OEIS Frontend

A271504 With a(1) = 1, a(n) is the LCM of all 0 < m < n for which a(m) divides n.

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