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A296758
Numbers whose base-15 digits d(m), d(m-1), ..., d(0) have #(rises) < #(falls); see Comments.
5
15, 30, 31, 45, 46, 47, 60, 61, 62, 63, 75, 76, 77, 78, 79, 90, 91, 92, 93, 94, 95, 105, 106, 107, 108, 109, 110, 111, 120, 121, 122, 123, 124, 125, 126, 127, 135, 136, 137, 138, 139, 140, 141, 142, 143, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 165
OFFSET
1,1
COMMENTS
A rise is an index i such that d(i) < d(i+1); a fall is an index i such that d(i) > d(i+1). The sequences A296756-A296758 partition the natural numbers. See the guide at A296712.
LINKS
EXAMPLE
The base-15 digits of 15^5 are 1, 0, 0, 0, 0, 0; here #(rises) = 0 and #(falls) = 1, so 15^5 is in the sequence.
MATHEMATICA
z = 200; b = 15; d[n_] := Sign[Differences[IntegerDigits[n, b]]];
Select[Range [z], Count[d[#], -1] == Count[d[#], 1] &] (* A296756 *)
Select[Range [z], Count[d[#], -1] < Count[d[#], 1] &] (* A296757 *)
Select[Range [z], Count[d[#], -1] > Count[d[#], 1] &] (* A296758 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Clark Kimberling, Jan 08 2018
STATUS
approved