A240597 Numbers k such that sigma(k) == k (mod 9).

1, 15, 24, 42, 60, 64, 69, 78, 90, 100, 114, 123, 133, 147, 153, 177, 186, 198, 222, 231, 240, 258, 259, 270, 276, 288, 289, 306, 339, 360, 366, 393, 402, 403, 414, 429, 438, 447, 459, 474, 477, 492, 495, 501, 507, 511, 522, 582, 588, 594, 600

Offset

1,2

Comments

That is, numbers k that satisfy the following:

A010878(k) = A105852(k) or A010878(k) = A010878(A000203(k)).

A010888(k) = A190998(k) or A010888(k) = A010888(A000203(k)).

Links

Ivan N. Ianakiev, Table of n, a(n) for n = 1..10000

Formula

A010888(a(n)) = A010888(A000203(a(n))).

A010888(a(n)) = A190998(a(n)).

Example

sigma(15) = 24. 24 == 15 (mod 9), therefore 15 is in the sequence.

Mathematica

Select[Range[1000], Mod[#, 9]==Mod[DivisorSigma[1, #], 9]&]

Crossrefs

Cf. A000203, A190998, A010878, A105852, A010888.

Sequence in context: A089952 A373406 A295160 * A162964 A067343 A247315

Adjacent sequences: A240594 A240595 A240596 * A240598 A240599 A240600

Keyword

easy,nonn

Author

Ivan N. Ianakiev, Sep 13 2014

Status

approved