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A296865 Numbers whose base-4 digits d(m), d(m-1), ..., d(0) have #(pits) > #(peaks); see Comments. 4
17, 18, 19, 33, 34, 35, 38, 39, 49, 50, 51, 54, 55, 59, 69, 70, 71, 74, 75, 79, 81, 82, 83, 133, 134, 135, 138, 139, 143, 145, 146, 147, 154, 155, 159, 161, 162, 163, 166, 167, 197, 198, 199, 202, 203, 207, 209, 210, 211, 218, 219, 223, 225, 226, 227, 230 (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 A296864-A296866 partition the natural numbers. See the guides at A296882 and A296712.
LINKS
EXAMPLE
The base-4 digits of 230 are 3, 2, 1, 2; here #(pits) = 1 and #(peaks) = 0, so 230 is in the sequence.
MATHEMATICA
z = 200; b = 4;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296864 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296865 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296866 *)
CROSSREFS
Sequence in context: A043853 A043861 A043870 * A188049 A098159 A241847
KEYWORD
nonn,base,easy
AUTHOR
Clark Kimberling, Jan 09 2018
STATUS
approved

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Last modified June 23 03:01 EDT 2024. Contains 373629 sequences. (Running on oeis4.)