A296876 Numbers whose base-8 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 72, 73, 74

Offset

1,2

Comments

A pit is an index i such that d(i-1) > d(i) < d(i+1); a peak is an index i such that d(i-1) < d(i) > d(i+1). The sequences A296876-A296878 partition the natural numbers. See the guides at A296882 and A296712.

Links

Clark Kimberling, Table of n, a(n) for n = 1..10000

Example

The base-8 digits of 74 are 1,1,2; here #(pits) = 0 and #(peaks) = 0, so 74 is in the sequence.

Mathematica

z = 200; b = 8;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296876 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296877 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296878 *)

Crossrefs

Cf. A296882, A296712, A296877, A296878.

Sequence in context: A090109 A130696 A146297 * A144972 A166719 A272159

Adjacent sequences: A296873 A296874 A296875 * A296877 A296878 A296879

Keyword

nonn,base,easy

Author

Clark Kimberling, Jan 09 2018

Status

approved