A333975 a(1) = 1, a(2) = 2 and for n > 2, a(n) is the smallest number not of the form OR(a(i),a(j)) for 1 <= i < j < n.

1, 2, 4, 7, 8, 11, 13, 14, 16, 19, 21, 22, 25, 26, 28, 32, 35, 37, 38, 41, 42, 44, 49, 50, 52, 56, 64, 67, 69, 70, 73, 74, 76, 81, 82, 84, 88, 97, 98, 100, 104, 112, 127, 128, 131, 133, 134, 137, 138, 140, 145, 146, 148, 152, 161, 162, 164, 168, 176, 191, 193, 194

Offset

1,2

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Mathematica

a[1] = 1; a[2] = 2;
a[n_] := a[n] =
  For[k = a[n - 1] + 1, True, k++,
   If[FreeQ[
     Table[BitOr[a[i], a[j]], {i, 1, n - 2}, {j, i + 1, n - 1}], k],
    Return[k]]];

Prog

(Python)
A333975_list, aset, m = [1, 2], set(), 2
for i in range(3, 10001):
    for j in range(i-2):
        aset.add(m|A333975_list[j])
    m += 1
    while m in aset:
        m += 1
    A333975_list.append(m) # Chai Wah Wu, Dec 21 2020

Crossrefs

Sequence in context: A229829 A000069 A344602 * A140137 A080308 A089559

Adjacent sequences: A333972 A333973 A333974 * A333976 A333977 A333978

Keyword

nonn

Author

Michal D. Kuczynski, Sep 03 2020

Status

approved