A246913 Numbers n such that sigma(n+sigma(n)) = 6*sigma(n).

831376, 3944688, 16956576, 17843616, 22591296, 25371360, 27870976, 51878736, 58877280, 64641984, 142990848, 164898720, 172821456, 181821024, 204330672, 276371200, 281613024, 301571424, 319848480, 326207700, 342237456, 346502520, 389165568, 389450880, 392110992

Offset: 1

Author

Jaroslav Krizek, Sep 07 2014

Keywords

• nonn

Comments

a(310) > 10^11. - Hiroaki Yamanouchi, Sep 11 2015

Examples

			Number 831376 (with sigma(831376) = 1985984) is in sequence because sigma(831376+sigma(831376)) = sigma(2817360) = 11915904 = 6*1985984.
		

Links

• Hiroaki Yamanouchi, Table of n, a(n) for n = 1..309

Crossrefs

Cf. A000203, A246456, A246909-A246912, A246914.

Programs

Magma

[n:n in[1..10^7] | SumOfDivisors(n+SumOfDivisors(n))eq 6*SumOfDivisors(n)]

PARI

for(n=1,10^7,if(sigma(n+sigma(n))==6*sigma(n),print1(n,", "))) \\ Derek Orr, Sep 07 2014

Extensions

a(5)-a(25) from Hiroaki Yamanouchi, Sep 11 2015