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A296887 Numbers whose base-11 digits d(m), d(m-1), ..., d(0) have #(pits) < #(peaks); see Comments. 4
143, 144, 154, 155, 156, 165, 166, 167, 168, 176, 177, 178, 179, 180, 187, 188, 189, 190, 191, 192, 198, 199, 200, 201, 202, 203, 204, 209, 210, 211, 212, 213, 214, 215, 216, 220, 221, 222, 223, 224, 225, 226, 227, 228, 231, 232, 233, 234, 235, 236, 237, 238 (list; graph; refs; listen; history; text; internal format)
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 A296885-A296887 partition the natural numbers. See the guides at A296712 and A296882.
LINKS
EXAMPLE
The base-11 digits of 17447 are 1,2,1,2,1; here #(pits) = 1 and #(peaks) = 2, so 17447 is in the sequence.
MATHEMATICA
z = 200; b = 11;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296885 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296886 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296887 *)
CROSSREFS
Sequence in context: A077494 A217142 A306090 * A293755 A160781 A217141
KEYWORD
nonn,base,easy
AUTHOR
Clark Kimberling, Jan 10 2018
STATUS
approved

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Last modified June 20 18:51 EDT 2024. Contains 373532 sequences. (Running on oeis4.)