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A296880 Numbers n whose base-9 digits d(m), d(m-1), ..., d(0) have #(pits) > #(peaks); see Comments. 4

%I

%S 82,83,84,85,86,87,88,89,163,164,165,166,167,168,169,170,173,174,175,

%T 176,177,178,179,244,245,246,247,248,249,250,251,254,255,256,257,258,

%U 259,260,264,265,266,267,268,269,325,326,327,328,329,330,331,332,335

%N Numbers n whose base-9 digits d(m), d(m-1), ..., d(0) have #(pits) > #(peaks); see Comments.

%C 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 A296879-A296881 partition the natural numbers. See the guides at A296882 and A296712.

%H Clark Kimberling, <a href="/A296880/b296880.txt">Table of n, a(n) for n = 1..10000</a>

%e The base-9 digits of 335 are 4,1,2; here #(pits) = 1 and #(peaks) = 0, so that 335 is in the sequence.

%t z = 200; b = 9;

%t d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];

%t Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296879 *)

%t Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296880 *)

%t Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296881 *)

%Y Cf. A296882, A296712, A296879, A296881.

%K nonn,base,easy

%O 1,1

%A _Clark Kimberling_, Jan 09 2018

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Last modified October 23 00:39 EDT 2021. Contains 348211 sequences. (Running on oeis4.)