A354141 Indices of terms in A352808 that are powers of 2.

1, 2, 3, 5, 9, 22, 31, 61, 121, 247, 479, 951, 1862, 3802, 7431, 15180, 29723, 59766, 118893, 239999, 475573, 959341, 1902293, 3835229, 7609175, 15268473, 30436701, 61001391

Offset: 1

Author

N. J. A. Sloane, May 18 2022

Keywords

• nonn
• more

Comments

Every power of 2 will eventually appear in A353730, so the sequence is infinite.

Links

• Rémy Sigrist, C++ program

Crossrefs

Cf. A352808, A353734.

Programs

Python

from itertools import count, islice
def ispow2(k): return bin(k).count("1") == 1
def agen(): # generator of terms
    A352808lst = [0, 1]; A352808set = {0, 1}
    k, mink, p = 1, 2, 2
    for n in count(2):
        if ispow2(k): yield n-1
        ahalf, k = A352808lst[n//2], mink
        while k in A352808set or k&ahalf: k += 1
        A352808lst.append(k); A352808set.add(k)
        while mink in A352808set: mink += 1
print(list(islice(agen(), 8))) # Michael S. Branicky, May 18 2022
(C++) See Links section.

Extensions

a(16)-a(22) from Michael S. Branicky, May 19 2022

a(23)-a(28) from Rémy Sigrist, May 21 2022