cp's OEIS Frontend

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.

A296874 Numbers whose base-7 digits d(m), d(m-1), ..., d(0) have #(pits) > #(peaks); see Comments.

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%I A296874 #7 Jan 21 2023 18:11:01
%S A296874 50,51,52,53,54,55,99,100,101,102,103,104,107,108,109,110,111,148,149,
%T A296874 150,151,152,153,156,157,158,159,160,164,165,166,167,197,198,199,200,
%U A296874 201,202,205,206,207,208,209,213,214,215,216,221,222,223,246,247,248
%N A296874 Numbers whose base-7 digits d(m), d(m-1), ..., d(0) have #(pits) > #(peaks); see Comments.
%C A296874 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 A296873-A296875 partition the natural numbers. See the guides at A296882 and A296712.
%H A296874 Clark Kimberling, <a href="/A296874/b296874.txt">Table of n, a(n) for n = 1..9999</a>
%e A296874 The base-7 digits of 248 are 5,0,3; here #(pits) = 0 and #(peaks) = 0, so 248 is in the sequence.
%t A296874 z = 200; b = 7;
%t A296874 d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
%t A296874 Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296873 *)
%t A296874 Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296874 *)
%t A296874 Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296875 *)
%Y A296874 Cf. A296882, A296712, A296873, A296875.
%K A296874 nonn,base,easy
%O A296874 1,1
%A A296874 _Clark Kimberling_, Jan 09 2018