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

1,1

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.

Links

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

Example

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

Prog

(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 */

Crossrefs

Cf. A005231, A048260.

Sequence in context: A157486 A086476 A279621 * A151721 A187743 A251829

Adjacent sequences: A168223 A168224 A168225 * A168227 A168228 A168229

Keyword

nonn

Author

William Rex Marshall, Nov 20 2009

Status

approved