A328753 Lexicographically earliest sequence of distinct positive numbers such that for any n > 0, the first nonzero digit of a(n+1)/a(n) is "2".

1, 2, 4, 8, 16, 32, 7, 14, 3, 6, 12, 24, 5, 10, 20, 40, 9, 18, 36, 72, 15, 30, 60, 13, 26, 52, 11, 22, 44, 88, 19, 38, 76, 17, 34, 68, 136, 28, 56, 112, 23, 46, 92, 21, 42, 84, 25, 50, 100, 27, 54, 108, 29, 58, 116, 31, 62, 124, 33, 66, 132, 35, 70, 140, 37

Offset

1,2

Comments

In other words, for any n > 0, we have an integer k such that floor(10^k * a(n+1)/a(n)) = 2.

Apparently, n -> a(n)/n has three accumulation points: 7/3, 7/6 and 7/12.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..1000

Example

The first terms, alongside a(n+1)/a(n), are:
  n   a(n)  a(n+1)/a(n)
  --  ----  -----------
   1     1  2
   2     2  2
   3     4  2
   4     8  2
   5    16  2
   6    32  0.21875
   7     7  2
   8    14  0.21428571...
   9     3  2
  10     6  2
  11    12  2
  12    24  0.20833333...

Crossrefs

See A328752 for similar sequences.

Sequence in context: A088976 A016020 A364628 * A119990 A378141 A380112

Adjacent sequences: A328750 A328751 A328752 * A328754 A328755 A328756

Keyword

nonn,base

Author

Rémy Sigrist, Oct 27 2019

Status

approved