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A230606 Numbers n such that sigma(n) = k*(n+1) for some integer k. 3
2, 3, 5, 7, 11, 13, 17, 19, 20, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 104, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers n such that A108775(n) = floor(sigma(n) / n) = sigma(n) mod n = A054024(n).

Union primes (A000040) and composite numbers A045768 (k = 1 for primes p, k = 2 for composite numbers).

LINKS

Jaroslav Krizek, Table of n, a(n) for n = 1..1000

EXAMPLE

20 is in sequence because sigma(20) = 42 = 2*20 + 2.

CROSSREFS

Cf. A000203(sigma(n)), A054024 (sigma(n) mod n), A108775.

Cf. A045768 (sigma(n) == 2 (mod n)).

Sequence in context: A242120 A259277 A152073 * A117289 A318719 A106317

Adjacent sequences:  A230603 A230604 A230605 * A230607 A230608 A230609

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Nov 29 2013

STATUS

approved

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Last modified May 19 23:16 EDT 2019. Contains 323411 sequences. (Running on oeis4.)