A168226 Even numbers which are the sum of two odd abundant numbers.

1890, 2520, 3150, 3780, 4410, 5040, 5670, 6300, 6720, 6930, 7350, 7380, 7560, 7770, 7980, 8010, 8190, 8370, 8400, 8610, 8640, 8820, 9000, 9030, 9240, 9270, 9360, 9450, 9630, 9660, 9870, 9900, 9990, 10080, 10260, 10290, 10500, 10530, 10620, 10710

Offset: 1

Author

William Rex Marshall, Nov 20 2009

Keywords

• nonn

Comments

Every even number >= 3706141025766237065507279802221127212928 is the sum of two odd abundant numbers. The largest even number which does not appear in this sequence is unknown.

Examples

			945 is the smallest odd abundant number, so 945 + 945 = 1890 is the first term in the sequence.
		

Links

• Donovan Johnson, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A005231, A048260.

Programs

PARI

mx=66240; x=vector(mx); k=144; v=vector(k); c=0; forstep(i=945, mx-1, 2, if(sigma(i)-2*i>0, c++; v[c]=i)); for(i=1, k, for(j=i, k, s=v[i]+v[j]; if(s<=mx, x[s]=1, next(2)))); c=0; forstep(n=1890, mx, 2, if(x[n]==1, c++; write("b168226.txt", c " " n))) /* Donovan Johnson, Jan 03 2013 */