This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A296884 #7 Jan 21 2023 20:28:35 %S A296884 120,121,130,131,132,140,141,142,143,150,151,152,153,154,160,161,162, %T A296884 163,164,165,170,171,172,173,174,175,176,180,181,182,183,184,185,186, %U A296884 187,190,191,192,193,194,195,196,197,198,230,231,232,240,241,242,243,250 %N A296884 Numbers whose base-10 digits d(m), d(m-1), ..., d(0) have #(pits) < #(peaks); see Comments. %C A296884 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. %H A296884 Clark Kimberling, <a href="/A296884/b296884.txt">Table of n, a(n) for n = 1..10000</a> %e A296884 The base-10 digits of 12121 are 1,2,1,2,1; here #(pits) = 1 and #(peaks) = 2, so 12121 is in the sequence. %t A296884 z = 200; b = 10; %t A296884 d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]]; %t A296884 Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296882 *) %t A296884 Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296883 *) %t A296884 Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296884 *) %Y A296884 Cf. A296882, A296712, A296882, A296883. %K A296884 nonn,base,easy %O A296884 1,1 %A A296884 _Clark Kimberling_, Jan 10 2018