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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A155047 a(1) = 1, a(2) = 2, then a(n) = largest prime factor of the partial sum up to a(n-1). 1
1, 2, 3, 3, 3, 3, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 11, 11, 11, 11, 11, 11, 13, 13, 13, 13, 13, 13, 17, 17, 17, 17, 17, 17, 19, 19, 19, 19, 19, 19, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 29, 29, 29, 29, 29, 29, 29, 29, 31, 31, 31, 31, 31, 31, 31, 31, 37, 37, 37, 37, 37, 37, 37, 37, 37, 37, 41 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MAPLE

A006530 := proc(n) max(op(numtheory[factorset](n))) ; end:

A155047 := proc(n) option remember; if n <=2 then n; else A006530( add(procname(i), i=1..n-1)) ; fi; end:

seq(A155047(n), n=1..120) ; # R. J. Mathar, Oct 23 2009

MATHEMATICA

nxt[{t_, a_}]:=Module[{lpf=FactorInteger[t][[-1, 1]]}, {t+lpf, lpf}]; Join[ {1}, NestList[ nxt, {3, 2}, 80][[All, 2]]] (* Harvey P. Dale, Aug 06 2018 *)

CROSSREFS

Sequence in context: A056206 A257245 A329245 * A029088 A253591 A129263

Adjacent sequences:  A155044 A155045 A155046 * A155048 A155049 A155050

KEYWORD

easy,nonn

AUTHOR

Giovanni Teofilatto, Jan 19 2009

EXTENSIONS

Extended by R. J. Mathar, Oct 23 2009

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 20 04:52 EDT 2021. Contains 348099 sequences. (Running on oeis4.)