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

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A134889 a(n)=the largest sum of two nontrivial divisors of n, if any, whose product equals n; otherwise, a(n)=n. 1
 1, 2, 3, 4, 5, 5, 7, 6, 6, 7, 11, 8, 13, 9, 8, 10, 17, 11, 19, 12, 10, 13, 23, 14, 10, 15, 12, 16, 29, 17, 31, 18, 14, 19, 12, 20, 37, 21, 16, 22, 41, 23, 43, 24, 18, 25, 47, 26, 14, 27, 20, 28, 53, 29, 16, 30, 22, 31, 59, 32, 61, 33, 24, 34, 18, 35, 67, 36, 26, 37, 71, 38, 73, 39 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A divisor of n other than 1 or n is called nontrivial. LINKS EXAMPLE There are two ways to write 12 as a product of two nontrivial divisors, i.e., 6*2 and 4*3. Since 8=6+2>4+3=7, we have a(12)=8. MATHEMATICA Table[If[Length[Divisors[n]] > 2, Max[Table[Divisors[n][[j]] + n/Divisors[n][[j]], {j, 2, Length[Divisors[n]] - 1}]], n], {n, 1, 100}] (* Stefan Steinerberger, Feb 04 2008 *) CROSSREFS Sequence in context: A337310 A001414 A134875 * A303702 A319057 A181894 Adjacent sequences:  A134886 A134887 A134888 * A134890 A134891 A134892 KEYWORD nonn,easy AUTHOR Joseph L. Pe, Feb 01 2008 EXTENSIONS More terms from Stefan Steinerberger, Feb 04 2008 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 December 1 07:14 EST 2020. Contains 338833 sequences. (Running on oeis4.)