This site is supported by donations to The OEIS Foundation.

 Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS". Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A048133 Least number which becomes prime or 4 after exactly n iterations of f(x) = sum of prime factors of x. 2
 2, 6, 8, 14, 26, 62, 134, 393, 1257, 4659, 9314, 27933, 167073, 334142, 4677862, 14033577, 56134292, 2133102298, 11788191218, 52541651594 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS f(x) = sum of prime factors with multiplicity, so that f(1500) = 2+2+3+5+5+5 = 22. Identical to the different-offset A121360 except for the second term. - Hans Havermann, Oct 05 2010 a(20) <= 536226160966. a(21) <= 2681130804805. a(22) <= 8512643845707. - Donovan Johnson LINKS CROSSREFS Sequence in context: A022112 A107019 A269831 * A199697 A135619 A067795 Adjacent sequences:  A048130 A048131 A048132 * A048134 A048135 A048136 KEYWORD nonn AUTHOR EXTENSIONS a(17) from Donovan Johnson, Apr 25 2010 Edited comment and a(18)-a(19) from Donovan Johnson, Oct 16 2010 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.