OFFSET
1,3
LINKS
Scott R. Shannon, Table of n, a(n) for n = 1..10000
EXAMPLE
a(8) = 2 as in the previous 8 - 1 = 7 terms there are two numbers that are not proper divisors of a(7) = 6, namely 4 and 6.
MAPLE
a:= proc(n) option remember; `if`(n=1, 1, (t-> add(
`if`(irem(t, a(j))>0 or t=a(j), 1, 0), j=1..n-1))(a(n-1)))
end:
seq(a(n), n=1..79); # Alois P. Heinz, May 10 2023
MATHEMATICA
nn = 120; a[1] = 1; Do[Set[{c, m}, {0, a[n - 1]}]; Do[If[And[# < m, Divisible[m, #]] &[a[i]], c++], {i, n}]; a[n] = n - c - 1, {n, 2, nn}]; Array[a, nn] (* Michael De Vlieger, May 10 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Scott R. Shannon, Apr 12 2023
STATUS
approved