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A296874
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Numbers whose base-7 digits d(m), d(m-1), ..., d(0) have #(pits) > #(peaks); see Comments.
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4
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50, 51, 52, 53, 54, 55, 99, 100, 101, 102, 103, 104, 107, 108, 109, 110, 111, 148, 149, 150, 151, 152, 153, 156, 157, 158, 159, 160, 164, 165, 166, 167, 197, 198, 199, 200, 201, 202, 205, 206, 207, 208, 209, 213, 214, 215, 216, 221, 222, 223, 246, 247, 248
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OFFSET
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1,1
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COMMENTS
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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.
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LINKS
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EXAMPLE
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The base-7 digits of 248 are 5,0,3; here #(pits) = 0 and #(peaks) = 0, so 248 is in the sequence.
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MATHEMATICA
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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 *)
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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