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A309227 Quasi-sociable numbers. 1
1215571544, 1270824975, 1467511664, 1512587175, 1530808335, 1579407344, 1638031815, 1727239544 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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

LINKS

Table of n, a(n) for n=1..8.

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

EXAMPLE

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

CROSSREFS

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

Sequence in context: A166735 A104933 A119333 * A195988 A262996 A022250

Adjacent sequences:  A309224 A309225 A309226 * A309228 A309229 A309230

KEYWORD

nonn,hard

AUTHOR

Donghwi Park, Jul 16 2019

STATUS

approved

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Last modified January 25 23:08 EST 2020. Contains 331270 sequences. (Running on oeis4.)