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

Author

Altug Alkan, Feb 17 2017

Keywords

• nonn
• more

Comments

Sequence is a result of investigation on the marked region in graph of A172398(A033950(n)) that is in Links section. Also there are other sequences that marked region has.

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

Crossrefs

Cf. A033950, A172398, A280634, A281663.

Extensions

a(10) from Giovanni Resta, Feb 17 2017