

A296875


Numbers whose base7 digits d(m), d(m1), ..., d(0) have #(pits) < #(peaks); see Comments.


4



63, 64, 70, 71, 72, 77, 78, 79, 80, 84, 85, 86, 87, 88, 91, 92, 93, 94, 95, 96, 119, 120, 121, 126, 127, 128, 129, 133, 134, 135, 136, 137, 140, 141, 142, 143, 144, 145, 175, 176, 177, 178, 182, 183, 184, 185, 186, 189, 190, 191, 192, 193, 194, 231, 232, 233
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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 A296873A296875 partition the natural numbers. See the guides at A296882 and A296712.


LINKS



EXAMPLE

The base7 digits of 233 are 4,5,2; here #(pits) = 0 and #(peaks) = 1, so 233 is in the sequence.


MATHEMATICA

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 *)


CROSSREFS



KEYWORD

nonn,base,easy


AUTHOR



STATUS

approved



