A309227 Quasi-sociable numbers.

1215571544, 1270824975, 1467511664, 1512587175, 1530808335, 1579407344, 1638031815, 1727239544

Offset: 1

Author

Donghwi Park, Jul 16 2019

Keywords

• nonn
• hard

Comments

The smallest quasi-sociable number cycle is {1215571544, 1270824975, 1467511664, 1530808335, 1579407344, 1638031815, 1727239544, 151258717, 1215571544}. They are the only known quasi-sociable numbers in 2019.

a(9) > 10^12, if it exists. - Giovanni Resta, Jul 25 2019

Examples

			1215571544 = 2^3 * 11 * 13813313
1270824975 = 3^2 * 5^2 * 7 * 19 * 42467
1467511664 = 2^4 * 19 * 599 * 8059
1530808335 = 3^3 * 5 * 7 * 1619903
1579407344 = 2^4 * 31^2 * 59 * 1741
1638031815 = 3^4 * 5 * 7 * 521 * 1109
1727239544 = 2^3 * 2671 * 80833
1512587175 = 3 * 5^2 * 11 * 1833439
		

Links

• David Moews, Reduced sociable numbers (e-mailed by Mitchell Dickerman on Sep. 10, 1997).

Crossrefs

Cf. A122726 (sociable numbers), A005276 (betrothed (or quasi-amicable) numbers).