A175431 Numbers m such that sigma(m) is not a nontrivial power, i.e., sigma(m) = A000203(n) is not equal a^b where a and b are greater than 1.

1, 2, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 23, 24, 25, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 67, 68, 69, 71, 72, 73, 74, 75, 76, 77, 78, 79

Offset

1,2

Comments

Complement of A065496.

A175432(a(n)) = 1 for n >= 1.

Links

Table of n, a(n) for n=1..72.

Example

Number 3 is not in the sequence because sigma(3) = 4 = 2^2.

Crossrefs

Cf. A000203, A065496, A175432.

Sequence in context: A323455 A133398 A138836 * A059921 A062289 A172284

Adjacent sequences: A175428 A175429 A175430 * A175432 A175433 A175434

Keyword

nonn

Author

Jaroslav Krizek, May 10 2010

Extensions

Extended by Ray Chandler, Aug 20 2010

Status

approved