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A296884 Numbers whose base-10 digits d(m), d(m-1), ..., d(0) have #(pits) < #(peaks); see Comments. 3
120, 121, 130, 131, 132, 140, 141, 142, 143, 150, 151, 152, 153, 154, 160, 161, 162, 163, 164, 165, 170, 171, 172, 173, 174, 175, 176, 180, 181, 182, 183, 184, 185, 186, 187, 190, 191, 192, 193, 194, 195, 196, 197, 198, 230, 231, 232, 240, 241, 242, 243, 250 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
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 A296882-A296883 partition the natural numbers. See the guides at A296712 and A296882.
LINKS
EXAMPLE
The base-10 digits of 12121 are 1,2,1,2,1; here #(pits) = 1 and #(peaks) = 2, so 12121 is in the sequence.
MATHEMATICA
z = 200; b = 10;
d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296882 *)
Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296883 *)
Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296884 *)
CROSSREFS
Sequence in context: A056456 A239535 A085218 * A117645 A157425 A030501
KEYWORD
nonn,base,easy
AUTHOR
Clark Kimberling, Jan 10 2018
STATUS
approved

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Last modified June 12 15:40 EDT 2024. Contains 373331 sequences. (Running on oeis4.)