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 A296904 #13 Jan 21 2023 02:23:09 %S A296904 401,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417, %T A296904 418,419,801,802,803,804,805,806,807,808,809,810,811,812,813,814,815, %U A296904 816,817,818,819,822,823,824,825,826,827,828,829,830,831,832,833,834,835 %N A296904 Numbers whose base-20 digits d(m), d(m-1), ..., d(0) have #(pits) > #(peaks); see Comments. %C A296904 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 A296903..A296905 partition the natural numbers. See the guides at A296712 and A296882. %H A296904 Clark Kimberling, <a href="/A296904/b296904.txt">Table of n, a(n) for n = 1..10000</a> %e A296904 The base-20 digits of 328822 are 2,1,2,1,2; here #(pits) = 2 and #(peaks) = 1, so 328822 is in the sequence. %t A296904 z = 200; b = 20; %t A296904 d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]]; %t A296904 Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &] (* A296903 *) %t A296904 Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &] (* A296904 *) %t A296904 Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &] (* A296905 *) %Y A296904 Cf. A296882, A296712, A296904, A296905. %K A296904 nonn,base,easy %O A296904 1,1 %A A296904 _Clark Kimberling_, Jan 12 2018