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.

A296887 Numbers whose base-11 digits d(m), d(m-1), ..., d(0) have #(pits) < #(peaks); see Comments.

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%I A296887 #7 Jan 21 2023 20:28:47
%S A296887 143,144,154,155,156,165,166,167,168,176,177,178,179,180,187,188,189,
%T A296887 190,191,192,198,199,200,201,202,203,204,209,210,211,212,213,214,215,
%U A296887 216,220,221,222,223,224,225,226,227,228,231,232,233,234,235,236,237,238
%N A296887 Numbers whose base-11 digits d(m), d(m-1), ..., d(0) have #(pits) < #(peaks); see Comments.
%C A296887 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 A296885-A296887 partition the natural numbers. See the guides at A296712 and A296882.
%H A296887 Clark Kimberling, <a href="/A296887/b296887.txt">Table of n, a(n) for n = 1..10000</a>
%e A296887 The base-11 digits of 17447 are 1,2,1,2,1; here #(pits) = 1 and #(peaks) = 2, so 17447 is in the sequence.
%t A296887 z = 200; b = 11;
%t A296887 d[n_] := Differences[Sign[Differences[IntegerDigits[n, b]]]];
%t A296887 Select[Range [z], Count[d[#], -2] == Count[d[#], 2] &]  (* A296885 *)
%t A296887 Select[Range [z], Count[d[#], -2] < Count[d[#], 2] &]   (* A296886 *)
%t A296887 Select[Range [z], Count[d[#], -2] > Count[d[#], 2] &]   (* A296887 *)
%Y A296887 Cf. A296882, A296712, A296885, A296886.
%K A296887 nonn,base,easy
%O A296887 1,1
%A A296887 _Clark Kimberling_, Jan 10 2018