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 A337460 Numbers k such that the k-th composition in standard order is a non-unimodal triple. 4
 22, 38, 44, 70, 76, 88, 134, 140, 148, 152, 176, 262, 268, 276, 280, 296, 304, 352, 518, 524, 532, 536, 552, 560, 592, 608, 704, 1030, 1036, 1044, 1048, 1064, 1072, 1096, 1104, 1120, 1184, 1216, 1408, 2054, 2060, 2068, 2072, 2088, 2096, 2120, 2128, 2144, 2192 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS These are triples matching the pattern (2,1,2), (3,1,2), or (2,1,3). A sequence of integers is unimodal if it is the concatenation of a weakly increasing and a weakly decreasing sequence. The k-th composition in standard order (graded reverse-lexicographic, A066099) is obtained by taking the set of positions of 1's in the reversed binary expansion of k, prepending 0, taking first differences, and reversing again. This gives a bijective correspondence between nonnegative integers and integer compositions. LINKS Eric Weisstein's World of Mathematics, Unimodal Sequence FORMULA Intersection of A014311 and A335373. EXAMPLE The sequence together with the corresponding triples begins:       22: (2,1,2)     296: (3,2,4)    1048: (6,1,4)       38: (3,1,2)     304: (3,1,5)    1064: (5,2,4)       44: (2,1,3)     352: (2,1,6)    1072: (5,1,5)       70: (4,1,2)     518: (7,1,2)    1096: (4,3,4)       76: (3,1,3)     524: (6,1,3)    1104: (4,2,5)       88: (2,1,4)     532: (5,2,3)    1120: (4,1,6)      134: (5,1,2)     536: (5,1,4)    1184: (3,2,6)      140: (4,1,3)     552: (4,2,4)    1216: (3,1,7)      148: (3,2,3)     560: (4,1,5)    1408: (2,1,8)      152: (3,1,4)     592: (3,2,5)    2054: (9,1,2)      176: (2,1,5)     608: (3,1,6)    2060: (8,1,3)      262: (6,1,2)     704: (2,1,7)    2068: (7,2,3)      268: (5,1,3)    1030: (8,1,2)    2072: (7,1,4)      276: (4,2,3)    1036: (7,1,3)    2088: (6,2,4)      280: (4,1,4)    1044: (6,2,3)    2096: (6,1,5) MATHEMATICA stc[n_]:=Differences[Prepend[Join@@Position[Reverse[IntegerDigits[n, 2]], 1], 0]]//Reverse; Select[Range[0, 1000], Length[stc[#]]==3&&MatchQ[stc[#], {x_, y_, z_}/; x>y

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Last modified July 24 11:17 EDT 2021. Contains 346273 sequences. (Running on oeis4.)