A296764 Numbers whose base-20 digits d(m), d(m-1), ..., d(0) have #(rises) < #(falls); see Comments.

20, 40, 41, 60, 61, 62, 80, 81, 82, 83, 100, 101, 102, 103, 104, 120, 121, 122, 123, 124, 125, 140, 141, 142, 143, 144, 145, 146, 160, 161, 162, 163, 164, 165, 166, 167, 180, 181, 182, 183, 184, 185, 186, 187, 188, 200, 201, 202, 203, 204, 205, 206, 207, 208

Offset: 1

Author

Clark Kimberling, Jan 08 2018

Keywords

• nonn
• base
• easy

Comments

A rise is an index i such that d(i) < d(i+1); a fall is an index i such that d(i) > d(i+1). The sequences A296762-A296764 partition the natural numbers. See the guide at A296712.

Examples

			The base-20 digits of 208 are 10,8; here #(rises) = 0 and #(falls) = 2, so 208 is in the sequence.
		

Links

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

Crossrefs

Cf. A296762, A296763, A296712.

Programs

Mathematica

z = 200; b = 20; d[n_] := Sign[Differences[IntegerDigits[n, b]]];
Select[Range [z], Count[d[#], -1] == Count[d[#], 1] &] (* A296762 *)
Select[Range [z], Count[d[#], -1] < Count[d[#], 1] &]  (* A296763 *)
Select[Range [z], Count[d[#], -1] > Count[d[#], 1] &]  (* A296764 *)