A243983 Sum of twin divisors of n.

0, 0, 4, 6, 0, 4, 0, 6, 4, 0, 0, 16, 0, 0, 9, 6, 0, 4, 0, 6, 4, 0, 0, 24, 0, 0, 4, 6, 0, 9, 0, 6, 4, 0, 12, 16, 0, 0, 4, 24, 0, 4, 0, 6, 9, 0, 0, 24, 0, 0, 4, 6, 0, 4, 0, 6, 4, 0, 0, 43, 0, 0, 20, 6, 0, 4, 0, 6, 4, 12, 0, 24, 0, 0, 9, 6, 0, 4, 0, 24, 4, 0, 0, 42, 0, 0, 4, 6, 0, 9

Offset

1,3

Comments

See A243865 for definition of twin divisor.

Links

Jens Kruse Andersen, Table of n, a(n) for n = 1..10000

Formula

a(n) = A000203(n) - A243984(n).

Example

The positive divisors of 40 are 1, 2, 4, 5, 8, 10, 20, 40. Of these, 2, 4, 8, 10, are twin divisors. So a(40) = the sum of these divisors, which is 24.

Crossrefs

Cf, A000203, A132748, A243865.

Sequence in context: A328227 A059750 A372919 * A117036 A016723 A194183

Adjacent sequences: A243980 A243981 A243982 * A243984 A243985 A243986

Keyword

nonn

Author

Juri-Stepan Gerasimov, Jun 16 2014

Status

approved