

A296865


Numbers n whose base4 digits d(m), d(m1), ..., 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
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OFFSET

1,1


COMMENTS

A pit is an index i such that d(i1) > d(i) < d(i+1); a peak is an index i such that d(i1) < d(i) > d(i+1). The sequences A296864A296866 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 base4 digits of 230 are 3, 2, 1, 2; here #(pits) = 1 and #(peaks) = 0, so that 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

Cf. A296882, A296712, A296864, A296866.
Sequence in context: A043853 A043861 A043870 * A188049 A098159 A241847
Adjacent sequences: A296862 A296863 A296864 * A296866 A296867 A296868


KEYWORD

nonn,base,easy


AUTHOR

Clark Kimberling, Jan 09 2018


STATUS

approved



