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 A308638 a(n) is the number of k > 0 such that n-1-2*k > 0 and the points (n-1-2*k, a(n-1-2*k)), (n-1-k, a(n-1-k)) and (n-1, a(n-1)) are aligned. 7
 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 2, 3, 1, 1, 1, 1, 3, 0, 1, 2, 3, 1, 4, 2, 1, 3, 2, 4, 1, 1, 2, 2, 2, 3, 3, 4, 2, 3, 3, 2, 4, 4, 0, 1, 3, 2, 1, 3, 4, 5, 3, 6, 5, 3, 2, 6, 0, 3, 6, 4, 0, 3, 5, 5, 5, 4, 3, 6, 3, 3, 7, 3, 2, 3, 3, 2, 2, 1, 3, 5, 6, 4, 2, 4, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,13 COMMENTS Is this sequence bounded? Are there infinitely many null values? LINKS Rémy Sigrist, Table of n, a(n) for n = 1..10000 Rémy Sigrist, Scatterplot of the first 25000000 terms Rémy Sigrist, C program for A308638 EXAMPLE The first terms, alongside the values of k such that (n-1-2*k, a(n-1-2*k)), (n-1-k, a(n-1-k)) and (n-1, a(n-1)), are: n a(n) k's -- ---- ----- 1 0 none 2 0 none 3 0 none 4 1 1 5 0 none 6 1 2 7 0 none 8 1 2 9 1 2 10 0 none 11 0 none 12 1 4 13 2 3,4 14 3 1,4,5 PROG (C) See Links section. CROSSREFS See A308639 for a similar sequence. Sequence in context: A122587 A276333 A347380 * A356320 A207572 A289623 Adjacent sequences: A308635 A308636 A308637 * A308639 A308640 A308641 KEYWORD nonn,look AUTHOR Rémy Sigrist, Jun 13 2019 STATUS approved

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Last modified August 12 08:23 EDT 2024. Contains 375085 sequences. (Running on oeis4.)