A058838 a(n) = 1 + sum of the anti-divisors of n.

1, 1, 3, 4, 6, 5, 11, 9, 9, 15, 13, 14, 20, 17, 19, 15, 29, 29, 19, 25, 23, 37, 35, 24, 40, 25, 43, 47, 25, 37, 43, 59, 49, 31, 53, 33, 51, 71, 53, 56, 42, 67, 57, 41, 87, 59, 61, 57, 73, 81, 43, 95, 89, 53, 75, 57, 75, 97, 91, 108, 58, 79, 113, 47, 85

Offset

1,3

Comments

See A066272 for definition of anti-divisor.

Links

Table of n, a(n) for n=1..65.

Jon Perry, Anti-divisors [Broken link]

Jon Perry, The Anti-divisor [Cached copy]

Jon Perry, The Anti-divisor: Even More Anti-Divisors [Cached copy]

Formula

a(n) = A066417(n) + 1.

Example

Consider n = 18: 2n-1, 2n, 2n+1 are 35, 36, 37 with odd divisors > 1 {5,7,35}, {3,9}, {37} respectively and quotients {7, 5, 1}, {12, 4}, {1}; so the anti-divisors of 18 are 4, 5, 7, 12. Therefore a(18) = 1 + 28 = 29.

Crossrefs

Cf. A066417, A066241, A066452.

Sequence in context: A336717 A332361 A360655 * A349372 A001177 A337878

Adjacent sequences: A058835 A058836 A058837 * A058839 A058840 A058841

Keyword

nonn

Author

Jon Perry, Dec 28 2001

Status

approved