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 A226239 Minimum m such that there exists an n-row subtractive triangle with distinct integers in 1..m. 1
 1, 3, 6, 10, 15, 22, 33, 44, 59, 76, 101, 125, 158 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS In an n-row subtractive triangle, there are n-i+1 integers in the i-th row. The integers in the first row are arbitrary. From the next row, the integers are the absolute difference between adjacent integers in the previous row. LINKS International Mathematical Olympiad, Problem 3 of IMO 2018. Denis Cazor, Algorithme en Français Denis Cazor, Algorithm in English EXAMPLE a(6)=22 because there is a 6-row subtractive triangle with distinct integers in [1..22] as follows: 1: 6 20 22 3 21 13 2: 14 2 19 18 8 3: 12 17 1 10 4: 5 16 9 5: 11 7 6: 4 However, there is no such triangle with distinct integers in [1..21]. CROSSREFS Cf. A035312, A035313. Sequence in context: A177100 A265071 A330910 * A209231 A137358 A143963 Adjacent sequences: A226236 A226237 A226238 * A226240 A226241 A226242 KEYWORD nonn,hard,more AUTHOR Yi Yang, Jun 01 2013 EXTENSIONS a(12) from Yi Yang, Mar 04 2015 a(13) from Denis Cazor, Aug 01 2022 STATUS approved

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Last modified March 29 03:40 EDT 2023. Contains 361596 sequences. (Running on oeis4.)