This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A172398 Number of partitions of n into the sum of two refactorable numbers. 0
 0, 1, 1, 1, 0, 0, 0, 0, 1, 2, 1, 0, 1, 1, 0, 1, 1, 1, 1, 2, 1, 0, 0, 1, 1, 2, 1, 0, 0, 1, 0, 1, 1, 0, 0, 2, 1, 1, 0, 0, 1, 2, 0, 1, 1, 0, 0, 3, 1, 0, 0, 1, 0, 1, 0, 0, 1, 2, 0, 1, 1, 1, 0, 2, 1, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,10 COMMENTS A number is refactorable if it is divisible by the number of its divisors. - Wesley Ivan Hurt, Jan 12 2013 LINKS FORMULA a(n) = sum(((1+floor(i/d(i)) - ceil(i/d(i))) * (1 + floor((n-i)/d(n-i)) - ceil((n-i)/d(n-i)))), i = 1..floor(n/2)). - Wesley Ivan Hurt, Jan 12 2013 EXAMPLE a(10)=2 because 10=1(refactorable)+9(refactorable)=2(refactorable)+8(refactorable). MAPLE with(numtheory); a:=n-> sum( ((1 + floor(i/tau(i)) - ceil(i/tau(i))) * (1 + floor((n-i)/tau(n-i)) - ceil((n-i)/tau(n-i))) ), i=1..floor(n/2)); CROSSREFS Cf. A033950, A129363, A175933. Sequence in context: A182641 A099200 A093578 * A070107 A044933 A025915 Adjacent sequences:  A172395 A172396 A172397 * A172399 A172400 A172401 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Nov 20 2010 EXTENSIONS Corrected by D. S. McNeil, Nov 20 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .