A282519 Refactorable numbers that are the sum of two refactorable numbers in exactly one way.
2, 9, 18, 24, 60, 88, 625, 1089, 2601, 1500625
Offset: 1
Examples
Refactorable number 1500625 is a term because 1500625 is the sum of two refactorable numbers in exactly one way, that is, 1500625 = 5^4 * 7^4 = 3^2 * 131^2 + 2^7 * 13 * 809.
Links
- Altug Alkan, Illustration of A172398(A033950(n))
- S. Colton, Refactorable Numbers - A Machine Invention, J. Integer Sequences, Vol. 2, 1999.
- Joshua Zelinsky, Tau Numbers: A Partial Proof of a Conjecture and Other Results , Journal of Integer Sequences, Vol. 5 (2002), Article 02.2.8
Extensions
a(10) from Giovanni Resta, Feb 17 2017
Comments