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 A101941 #11 May 26 2023 08:49:44 %S A101941 0,0,0,0,0,3,0,0,0,1,-1,1,-1,0,0,0,0,1,-1,0,0,0,-1,1,-1,1,-1,1,-1,11, %T A101941 0,0,0,0,0,0,-3,0,0,0,-1,11,-1,0,0,0,-1,1,-1,0,0,0,-3,0,0,0,0,0,-1,5, %U A101941 -1,0,0,-2,0,3,-2,0,0,3,-1,1,-1 %N A101941 Peak-trough transform of the omega sequence (A001221). %C A101941 I define the peak-trough transform (b(n)) of sequence (c(n)) as follows. If c(n) is greater than both of its immediate neighbors, b(n) is defined as the largest k <= n-1 such that c(n) is greater than its k nearest neighbors both before and after it in the sequence. (c(n) is said to be a k-peak of the sequence). If c(n) is smaller than both of its immediate neighbors, b(n) is defined as -k, where k is the largest k <= n-1 such that c(n) is smaller than its k nearest neighbors both before and after it in the sequence. (c(n) is said to be a k-trough of the sequence). Otherwise, b(n) is 0. (Note difference between a k-peak and a k-apex as defined by Joseph L. Pe in A076759). %Y A101941 Cf. A001221, A023188, A076759, A101932. %K A101941 sign %O A101941 1,6 %A A101941 _Neil Fernandez_, Dec 22 2004 %E A101941 Corrected by _Peter Munn_, May 26 2023