A246910 Numbers n such that sigma(n+sigma(n)) = 3*sigma(n).

1, 7, 26, 30, 42, 54, 69, 78, 84, 94, 102, 103, 114, 138, 140, 174, 222, 258, 354, 364, 474, 476, 498, 520, 532, 534, 582, 618, 644, 650, 762, 764, 812, 834, 847, 894, 978, 1002, 1036, 1038, 1050, 1182, 1185, 1194, 1204, 1214, 1362, 1372, 1398, 1434, 1487

Offset

1,2

Comments

A246914 gives the primes in this sequence.

Links

Martin Møller Skarbiniks Pedersen, Table of n, a(n) for n = 1..1000

Example

Number 26 (with sigma(26) = 42) is in sequence because sigma(26+sigma(26)) = sigma(68) = 126 = 3*42.

Maple

with(numtheory): A246910:=n->`if`(sigma(n+sigma(n)) = 3*sigma(n), n, NULL): seq(A246910(n), n=1..5000); # Wesley Ivan Hurt, Sep 07 2014

Prog

(Magma) [n:n in[1..10000] | SumOfDivisors(n+SumOfDivisors(n)) eq 3*SumOfDivisors(n)]
(PARI)
for(n=1, 10^4, if(sigma(n+sigma(n))==3*sigma(n), print1(n, ", "))) \\ Derek Orr, Sep 07 2014

Crossrefs

Cf. A000203, A246456, A246909, A246911, A246912, A246913, A246914, A272027.

Sequence in context: A262109 A276614 A230399 * A098127 A283427 A131905

Adjacent sequences: A246907 A246908 A246909 * A246911 A246912 A246913

Keyword

nonn

Author

Jaroslav Krizek, Sep 07 2014

Status

approved