The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A118291 a(1) = 1. a(n) = number of terms among the sequence's first (n-1) terms which are divisible by the largest prime dividing a(n-1), or which are divisible by 1 if a(n-1)= 1. 2
 1, 1, 2, 1, 4, 2, 3, 1, 8, 4, 5, 1, 12, 2, 7, 1, 16, 8, 9, 3, 4, 10, 2, 12, 5, 3, 6, 7, 2, 15, 4, 16, 17, 1, 34, 2, 19, 1, 38, 2, 21, 3, 10, 5, 6, 11, 1, 47, 1, 49, 4, 24, 12, 13, 1, 55, 2, 27, 14, 5, 8, 29, 1, 63, 6, 16, 31, 1, 68, 3, 17, 4, 33, 3, 19, 3, 20, 9, 21, 7, 8, 35, 9, 23, 1, 85, 5, 12 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS If a(n-1) = 1, then a(n) = n-1, obviously. LINKS Table of n, a(n) for n=1..88. EXAMPLE a(13)= 12. So a(14) = the number of terms among the first 13 terms which are divisible by the largest prime dividing 12 (which is 3). a(7)=3 and a(13) = 12 are the two terms each divisible by 3, so a(14) = 2. MAPLE A006530 := proc(n) local ifs, i ; if n <= 3 then n ; else ifs := ifactors(n)[2] ; max( seq(op(1, i), i=ifs)) ; fi ; end: A118291 := proc(n) local a, anxt, i ; a := [1, 1] ; while nops(a) < n do anxt := 0 ; for i in a do if i mod A006530(op(-1, a)) = 0 then anxt := anxt+1 ; fi ; od: a := [op(a), anxt] ; od; a ; end: A118291(200) ; # R. J. Mathar, Sep 06 2007 CROSSREFS Cf. A118290. Sequence in context: A128520 A269370 A123755 * A118290 A208569 A341392 Adjacent sequences: A118288 A118289 A118290 * A118292 A118293 A118294 KEYWORD nonn AUTHOR Leroy Quet, Apr 22 2006 EXTENSIONS More terms from R. J. Mathar, Sep 06 2007 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 May 24 14:39 EDT 2024. Contains 372778 sequences. (Running on oeis4.)