A293541 a(1)=1; for n>1, a(n) = least integer greater than a(n-1) such that the numbers of divisors of the pairwise sums of a(1),...,a(n) are all distinct.

1, 3, 15, 909, 306915, 36181647, 25342642989

Offset: 1

Author

Logan J. Kleinwaks, Oct 11 2017

Keywords

• more
• nonn

Examples

			Let d(n) be the number of divisors of n.  Then a(2)!=2 because d(1+1)=d(1+2)=2. a(2)=3 because d(1+1)=2, d(1+3)=3, and d(3+3)=4 are all distinct.
		

Crossrefs

Cf. A000005, A293542, A005282.