A122544 Smallest positive number divisible by n which is not of the form a(i) or a(i)+a(j) for i and j <= n-1.

1, 4, 3, 12, 10, 18, 35, 32, 9, 40, 55, 48, 26, 84, 105, 112, 17, 54, 76, 100, 231, 198, 23, 120, 25, 156, 162, 280, 203, 150, 31, 192, 264, 68, 245, 288, 222, 418, 468, 440, 82, 294, 301, 352, 405, 368, 141, 432, 98, 600, 714, 520, 424, 702, 275, 672, 513, 928, 177

Offset: 1

Author

N. J. A. Sloane, Sep 20 2006

Keywords

• nonn

Comments

Same as A122537, except that a(n) is allowed to be less than a(n-1) (but not equal to it, or any other previous term).

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A122537, A122545 (a(n)/n), A122546 (complement), A122804.

Programs

Maple

a:=array(0..100000); m:=array(0..100000); hit:=array(0..100000); B:=100000; M:=120;
for n from 1 to B do hit[n]:=0; od:
a[1]:=1; m[1]:=1; a[2]:=4; m[2]:=2; hit[2]:=1; hit[5]:=1; hit[8]:=1; hit[1]:=1; hit[4]:=1;
for n from 3 to M do i:=n; while hit[i] = 1 do i:=i+n; od; a[n]:= i; m[n]:= i/n; hit[i]:=1;
for j from 1 to n do hit[a[j]+i]:=1; od; od:
t1:=[seq(a[n],n=1..M)]; t2:=[seq(m[n],n=1..M)];

Mathematica

f[s_] := Block[{n, k},k = n = Length[s] + 1;While[MemberQ[Union[s, Plus @@@ Tuples[s, 2]], k], k += n];Append[s, k]];Nest[f, {1}, 60] (* Ray Chandler, Sep 29 2006 *)