A328756 Lexicographically earliest sequence of distinct positive numbers such that for any n > 0, the first nonzero digit of a(n+1)/a(n) is "5".

1, 5, 25, 13, 7, 4, 2, 10, 50, 26, 14, 8, 40, 20, 11, 6, 3, 15, 75, 38, 19, 95, 48, 24, 12, 60, 30, 16, 9, 45, 23, 115, 58, 29, 17, 85, 43, 22, 110, 55, 28, 140, 70, 35, 18, 90, 46, 27, 135, 68, 34, 170, 86, 44, 220, 111, 56, 31, 155, 78, 39, 21, 105, 53, 265

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)) = 5.

The scatterplot of n -> a(n)/n shows 10 quivering lines.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Example

The first terms, alongside a(n+1)/a(n), are:
  n   a(n)  a(n+1)/a(n)
  --  ----  -----------
   1     1  5
   2     5  5
   3    25  0.52
   4    13  0.538461...
   5     7  0.571428...
   6     4  0.5
   7     2  5
   8    10  5
   9    50  0.52
  10    26  0.538461...
  11    14  0.571428...
  12     8  5

Crossrefs

See A328752 for similar sequences.

Sequence in context: A070379 A143254 A070385 * A070378 A070384 A337392

Adjacent sequences: A328753 A328754 A328755 * A328757 A328758 A328759

Keyword

nonn,base

Author

Rémy Sigrist, Oct 27 2019

Status

approved