A287611 Numbers which are twice an Ulam number but not the sum of two distinct Ulam numbers.

2, 94, 96, 194, 204, 678, 712, 2310, 7446

Offset: 1

Author

Enrique Navarrete, May 27 2017

Keywords

• nonn
• more

Comments

The sequence could also be described as numbers that have no representation as a sum of two distinct Ulam numbers, but have a "pseudo-representation" u + u, where u is an Ulam number.

a(10), if it exists, is larger than 5*10^7. - Giovanni Resta, May 31 2017

Examples

			204 is in the sequence since it can't be written as the sum of two distinct Ulam numbers, but 204 = 102 + 102, where 102 is an Ulam number.
		

Crossrefs

Cf. A002858, A285882.

Formula

a(n) = A285882(n)/2. - Giovanni Resta, May 31 2017