A068195 Numbers of the form n(n+1)/2 whose only representation as a sum of 2 or more consecutive positive integers is 1+2+...+n.

1, 3, 6, 10, 28, 136, 496, 8128, 32896, 33550336, 2147516416, 8589869056, 137438691328, 2305843008139952128, 2658455991569831744654692615953842176

Offset

1,2

Comments

Consists of 1, even perfect numbers and numbers of the form n(n+1)/2 where n+1 is a Fermat prime. (See A068194 for proof.)

Links

Table of n, a(n) for n=1..15.

Jon Perry, Erdos-Moser

Crossrefs

Cf. A000396, A000668, A019434, A068194.

Record values in A082184.

Sequence in context: A197435 A240514 A115887 * A080506 A109163 A109490

Adjacent sequences: A068192 A068193 A068194 * A068196 A068197 A068198

Keyword

nonn

Author

Jon Perry, Feb 19 2002

Extensions

Edited by Dean Hickerson, Feb 22 2002

Status

approved