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 A296888 #7 Jan 21 2023 20:28:51 %S A296888 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26, %T A296888 27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49, %U A296888 50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67 %N A296888 Numbers whose base-12 digits d(m), d(m-1), ..., d(0) have #(pits) = #(peaks); see Comments. %C A296888 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 A296888-A296890 partition the natural numbers. See the guides at A296712 and A296882. %H A296888 Clark Kimberling, <a href="/A296888/b296888.txt">Table of n, a(n) for n = 1..10000</a> %e A296888 The base-12 digits of 2030 are 1,2,1,2; here #(pits) = 1 and #(peaks) = 1, so 2030 is in the sequence. %t A296888 z = 200; b = 12; %t A296888 d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]]; %t A296888 Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296888 *) %t A296888 Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296889 *) %t A296888 Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296890 *) %Y A296888 Cf. A296882, A296712, A296889, A296890. %K A296888 nonn,base,easy %O A296888 1,2 %A A296888 _Clark Kimberling_, Jan 10 2018