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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A120679 a(1)=1. a(n) = a(n-1) + d(a(k)), where d(m) is the number of positive divisors of m and d(a(k)) is the maximum value over the k's where 1<=k <=n-1. 2
1, 2, 4, 7, 10, 14, 18, 24, 32, 40, 48, 58, 68, 78, 88, 98, 108, 120, 136, 152, 168, 184, 200, 216, 232, 248, 264, 280, 296, 312, 328, 344, 360, 384, 408, 432, 456, 480, 504, 528, 552, 576, 600, 624, 648, 672, 696, 720, 750, 780, 810, 840, 872, 904, 936, 968 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
EXAMPLE
The number of positive divisors of the first 13 terms of this sequence form the sequence 1,2,3,2,4,4,6,8,6,8,10,4,6 (sequence A120680). Of these terms, 10 is the largest. So a(14) = a(13) + 10 = 78.
MAPLE
A120679 := proc(maxn) local d, p, a, n; a := [1] ; d := 1 ; for n from 2 to maxn do d := max(d, numtheory[tau](a[n-1])) ; a := [op(a), a[n-1]+d] ; od ; RETURN(a) ; end: nmax := 80 : a := A120679(nmax) : for n from 1 to nmax do printf("%d, ", a[n]) ; od ; # R. J. Mathar, Aug 17 2006
CROSSREFS
Cf. A120680.
Sequence in context: A227353 A183136 A144873 * A145106 A127723 A076268
KEYWORD
nonn
AUTHOR
Leroy Quet, Jun 24 2006
EXTENSIONS
More terms from R. J. Mathar, Aug 17 2006
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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 00:26 EDT 2024. Contains 371264 sequences. (Running on oeis4.)