The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A329724 Sequence of distinct integers such that a(1) = 0, and for k = 1, 2, ..., the last term so far and the k next terms are in arithmetic progression with common difference d_k such that abs(d_k) is as small as possible and d_k > 0 iff k is odd. 1
 0, 1, -1, -3, 2, 7, 12, 11, 10, 9, 8, 13, 18, 23, 28, 33, 19, 5, -9, -23, -37, -51, -50, -49, -48, -47, -46, -45, -44, -52, -60, -68, -76, -84, -92, -100, -108, -83, -58, -33, -8, 17, 42, 67, 92, 117, 116, 115, 114, 113, 112, 111, 110, 109, 108, 107, 118, 129 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS The sequence zigzags and A000124 corresponds to the indices of its extrema. Will this sequence change sign infinitely often? LINKS Rémy Sigrist, Table of n, a(n) for n = 1..10012 Rémy Sigrist, C++ program for A329724 Rémy Sigrist, Scatterplot of the first 39582754 terms EXAMPLE The first terms, alongside the corresponding k and d_k, are:   n   a(n)  k    d_k   --  ----  ---  ---    1     0  N/A  N/A    2     1    1    1    3    -1    2   -2    4    -3    2   -2    5     2    3    5    6     7    3    5    7    12    3    5    8    11    4   -1    9    10    4   -1   10     9    4   -1   11     8    4   -1   12    13    5    5   13    18    5    5   14    23    5    5   15    28    5    5   16    33    5    5 PROG (C++) See Links section. CROSSREFS Cf. A000124, A001057. Sequence in context: A182871 A143329 A053440 * A143332 A255919 A212189 Adjacent sequences:  A329721 A329722 A329723 * A329725 A329726 A329727 KEYWORD sign,look AUTHOR Rémy Sigrist, Nov 19 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 1 03:36 EDT 2020. Contains 337441 sequences. (Running on oeis4.)