A238227 Numbers n such that if x=sigma(n)-tau(n)-n then n=sigma(x)-tau(x)-x.

1, 56, 66, 70, 992, 1012, 2260, 2516, 6042, 6902, 7192, 7210, 7232, 7750, 7912, 8178, 9086, 10792, 12198, 13706, 17272, 30592, 32778, 33352, 35032, 40166, 44034, 45010, 46670, 47710, 55374, 62296, 63688, 65570, 114256, 132916, 133892, 138244, 141236, 146804, 155572

Offset

1,2

Comments

If the second term (4) is not considered, A056075 is almost a subset of this sequence: it lists the fixed points of the transform n -> sigma(n)-tau(n)-n.

Links

Amiram Eldar, Table of n, a(n) for n = 1..1001 (terms 1..50 from Paolo P. Lava)

Example

Fixed points: 56, 7192, 7232, 7912, 10792, ...
sigma(66) = 144, tau(66) = 8 and 144 - 8 - 66 = 70.
sigma(70) = 144, tau(70) = 8 and 144 - 8 - 70 = 66.

Maple

with(numtheory); P:=proc(q)local a, n;
for n from 1 to q do a:=sigma(n)-tau(n)-n;
if sigma(a)-tau(a)-a=n then print(n);
fi; od; end: P(10^6);

Crossrefs

Cf. A000005, A000203, A056075, A238225, A238226, A238228, A238229, A238230.

Sequence in context: A043251 A044031 A256515 * A216855 A219800 A050440

Adjacent sequences: A238224 A238225 A238226 * A238228 A238229 A238230

Keyword

nonn

Author

Paolo P. Lava, Feb 20 2014

Status

approved