The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A309226 Index of n-th low point in A008348 (see Comments for definition). 10
 0, 3, 8, 21, 56, 145, 366, 945, 2506, 6633, 17776, 48521, 133106, 369019, 1028404, 2880287, 8100948, 22877145, 64823568, 184274931, 525282740, 1501215193, 4299836186, 12340952049, 35486796312, 102220582465, 294917666854, 852123981581, 2465458792768 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS A "low point" in a sequence is a term which is less than the previous term (this condition is skipped for the initial term) and which is followed by two or more increases. This concept is useful for the analysis of sequences (such as A005132, A008344, A008348, A022837, A076042, A309222, etc.) which have long runs of terms which alternately rise and fall. LINKS FORMULA a(n) = A135025(n-1)-1. MAPLE blocks := proc(a, S) local b, c, d, M, L, n; # Given a list a, whose leading term has index S, return [b, c, d], where b lists the indices of the low points in a, c lists the values of a at the low points, and d lists the length of runs between the low points. b:=[]; c:=[]; d:=[]; L:=1; # is a[1] a low point?    n:=1;    if( (a[n+1]>a[n]) and (a[n+2]>a[n+1]) ) then    b:=[op(b), n+S-1]; c:=[op(c), a[n]]; d:=[op(d), n-L]; L:=n; fi; for n from 2 to nops(a)-2 do # is a[n] a low point?    if( (a[n-1]>a[n]) and (a[n+1]>a[n]) and (a[n+2]>a[n+1]) ) then    b:=[op(b), n+S-1]; c:=[op(c), a[n]]; d:=[op(d), n-L]; L:=n; fi; od; [b, c, d]; end; # Let a := [0, 2, 5, 0, 7, 18, 5, 22, 3, 26, 55, 24, ...]; be a list of the first terms in A008348 blocks(a, 0)[1]; # the present sequence blocks(a, 0)[2]; # A324782 blocks(a, 0)[3]; # A324783 CROSSREFS Cf. A005132, A008344, A008348, A022837, A076042, A135025, A309222, A324782, A324783. Sequence in context: A278613 A072632 A001671 * A278616 A278615 A090413 Adjacent sequences:  A309223 A309224 A309225 * A309227 A309228 A309229 KEYWORD nonn,more AUTHOR N. J. A. Sloane, Sep 01 2019 EXTENSIONS a(17)-a(28) from Giovanni Resta, Oct 02 2019 Modified definition to make offset 0. - N. J. A. Sloane, Oct 02 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 13 05:18 EDT 2022. Contains 356077 sequences. (Running on oeis4.)