OFFSET
1,1
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
FORMULA
a(n) = A285882(n)/2. - Giovanni Resta, May 31 2017
EXAMPLE
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
KEYWORD
nonn,more
AUTHOR
Enrique Navarrete, May 27 2017
STATUS
approved