A296875 Numbers whose base-7 digits d(m), d(m-1), ..., d(0) have #(pits) < #(peaks); see Comments.

63, 64, 70, 71, 72, 77, 78, 79, 80, 84, 85, 86, 87, 88, 91, 92, 93, 94, 95, 96, 119, 120, 121, 126, 127, 128, 129, 133, 134, 135, 136, 137, 140, 141, 142, 143, 144, 145, 175, 176, 177, 178, 182, 183, 184, 185, 186, 189, 190, 191, 192, 193, 194, 231, 232, 233

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 233 are 4,5,2; here #(pits) = 0 and #(peaks) = 1, so 233 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, A296874.

Sequence in context: A365397 A332926 A112816 * A346803 A263282 A295695

Adjacent sequences: A296872 A296873 A296874 * A296876 A296877 A296878

Keyword

nonn,base,easy

Author

Clark Kimberling, Jan 09 2018

Status

approved