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 A232361 #15 Sep 23 2015 09:38:40 %S A232361 590868,586496,392956,392612,369532,371872,348760,92820,98000,97424, %T A232361 268428,7855172,11351516,12763068,12778820,12778872,12778940,14485860, %U A232361 16971756,16976632,17062548,17065428,16934020,33084456,33100460,33116544,32916668,32921404 %N A232361 Peak values in A232221. %C A232361 max{A232221(A232359(n)-1),A232221(A232359(n)+1)} < a(n). %C A232361 First entry < 0: a(77) = -279411084. %H A232361 Reinhard Zumkeller, <a href="/A232361/b232361.txt">Table of n, a(n) for n = 1..890</a> %F A232361 a(n) = A232221(A232359(n)). %e A232361 n = 17: A232359(17) = 3628, a(17) = 12778940: %e A232361 A232221(3628) = 12778940, whereas A232221(3628-1) = 12778756 and A232221(3628+1) = 12778920 are both less than a(17), with altitude differences 184 and 20. Therefore a(17) is the altitude of a peak in A232221. It can be identified in oeis.org/A232221/graph as top of a foothill. %e A232361 n = 461: A232359(461) = 373250, a(461) = -2419822248: %e A232361 A232221(373250) = -2419822248, whereas A232221(373250-1) = -2419823140 and A232221(373250+1) = -2419823192 are both less than a(461), with altitude differences 892 and 944. Therefore a(461) is the altitude of a peak in A232221. It can be identified in Hans Havermann's third plot (< 1.5 million) as the below-axis peak under the 4 of 400000. %o A232361 (Haskell) %o A232361 a232361 n = a232361_list !! (n-1) -- a232361_list is defined in A232359. %K A232361 sign %O A232361 1,1 %A A232361 _Reinhard Zumkeller_, Nov 24 2013