A296874 Numbers whose base-7 digits d(m), d(m-1), ..., d(0) have #(pits) > #(peaks); see Comments.

50, 51, 52, 53, 54, 55, 99, 100, 101, 102, 103, 104, 107, 108, 109, 110, 111, 148, 149, 150, 151, 152, 153, 156, 157, 158, 159, 160, 164, 165, 166, 167, 197, 198, 199, 200, 201, 202, 205, 206, 207, 208, 209, 213, 214, 215, 216, 221, 222, 223, 246, 247, 248

Offset

1,1

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 A296873-A296875 partition the natural numbers. See the guides at A296882 and A296712.

Links

Clark Kimberling, Table of n, a(n) for n = 1..9999

Example

The base-7 digits of 248 are 5,0,3; here #(pits) = 0 and #(peaks) = 0, so 248 is in the sequence.

Mathematica

z = 200; b = 7;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296873 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296874 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296875 *)

Crossrefs

Cf. A296882, A296712, A296873, A296875.

Sequence in context: A171652 A078289 A043618 * A134691 A139182 A294297

Adjacent sequences: A296871 A296872 A296873 * A296875 A296876 A296877

Keyword

nonn,base,easy

Author

Clark Kimberling, Jan 09 2018

Status

approved