A272697 Powers of 2 with exactly one odd decimal digit.

1, 16, 32, 128, 256, 1024, 4096, 262144, 524288, 8388608

Offset

1,2

Comments

Inspired by A068994 (Powers of 2 such that number of odd digits is 0).

No additional terms up to 2^10000.

No additional terms < 2^500000. - Chai Wah Wu, May 22 2016

No additional terms < 2^(10^10). - Michael S. Branicky, Apr 16 2023

Links

Table of n, a(n) for n=1..10.

Mathematica

Select[2^Range[0, 50000], Total@ Pick[DigitCount@ #, {1, 0, 1, 0, 1, 0, 1, 0, 1, 0}, 1] == 1 &] (* Michael De Vlieger, May 04 2016 *)

Prog

(Ruby)
ary = [1]
s = 1
(1..10 ** 4).each{|i|
  s *= 2
  j = s.to_s.split('').map(&:to_i).select{|i| i % 2 == 1}.size
  ary << s if j == 1
}
p ary

Crossrefs

Cf. A068994, A272698.

Sequence in context: A235056 A115686 A088112 * A232510 A339356 A282832

Adjacent sequences: A272694 A272695 A272696 * A272698 A272699 A272700

Keyword

nonn,base

Author

Seiichi Manyama, May 04 2016

Status

approved