A211658 Nonprime numbers k such that value of sigma(k) is unique; sigma(k) = A000203(k) = sum of divisors of k.

1, 4, 8, 9, 12, 18, 22, 27, 32, 36, 45, 49, 50, 64, 72, 81, 91, 98, 100, 106, 121, 128, 129, 133, 134, 146, 148, 152, 162, 169, 171, 192, 200, 202, 217, 218, 219, 243, 256, 259, 262, 268, 274, 288, 289, 292, 301, 314, 324, 333, 338, 343, 361, 381, 386, 388

Offset

1,2

Comments

Complement of A066076 with respect to A211656.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

Number 36 is in the sequence because sigma(36) = 91 and there is no other number m with sigma(m) = 91.
Number 6 is not in the sequence because sigma(6) = 12 and 12 is also sigma(11).

Crossrefs

Cf. A000203, A066076, A211656, A211657, A211659, A211660.

Sequence in context: A252849 A082293 A048944 * A235054 A292364 A071835

Adjacent sequences: A211655 A211656 A211657 * A211659 A211660 A211661

Keyword

nonn

Author

Jaroslav Krizek, Apr 20 2012

Status

approved