cp's OEIS Frontend

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

%I A354141 #25 May 21 2022 14:53:17
%S A354141 1,2,3,5,9,22,31,61,121,247,479,951,1862,3802,7431,15180,29723,59766,
%T A354141 118893,239999,475573,959341,1902293,3835229,7609175,15268473,
%U A354141 30436701,61001391
%N A354141 Indices of terms in A352808 that are powers of 2.
%C A354141 Every power of 2 will eventually appear in A353730, so the sequence is infinite.
%H A354141 Rémy Sigrist, <a href="/A354141/a354141.txt">C++ program</a>
%o A354141 (Python)
%o A354141 from itertools import count, islice
%o A354141 def ispow2(k): return bin(k).count("1") == 1
%o A354141 def agen(): # generator of terms
%o A354141     A352808lst = [0, 1]; A352808set = {0, 1}
%o A354141     k, mink, p = 1, 2, 2
%o A354141     for n in count(2):
%o A354141         if ispow2(k): yield n-1
%o A354141         ahalf, k = A352808lst[n//2], mink
%o A354141         while k in A352808set or k&ahalf: k += 1
%o A354141         A352808lst.append(k); A352808set.add(k)
%o A354141         while mink in A352808set: mink += 1
%o A354141 print(list(islice(agen(), 8))) # _Michael S. Branicky_, May 18 2022
%o A354141 (C++) See Links section.
%Y A354141 Cf. A352808, A353734.
%K A354141 nonn,more
%O A354141 1,2
%A A354141 _N. J. A. Sloane_, May 18 2022
%E A354141 a(16)-a(22) from _Michael S. Branicky_, May 19 2022
%E A354141 a(23)-a(28) from _Rémy Sigrist_, May 21 2022