OFFSET
1,2
COMMENTS
There are only a finite number of such pairs for each n. A180330(n) is the smallest value of 2^n * pq which is part of an amicable pair. The terms in this sequence equal the count of such amicable pairs in Pedersen's table up to n=22, after which the table stops being a complete list of all amicable pairs of the form 2^n * pq. Currently, Pedersen's table lists 4 such amicable pairs for n=23 when there are actually 8 pairs.
LINKS
J. M. Pedersen, Regular type (2,2) amicable pairs
EXAMPLE
Eight pairs for n=23, with new ones indicated by *:
(112072375885373577887744, 112072384861110016147456) *
(1268674663237438821892096, 1268674685089131637243904)
(207428765646084356836425728, 207428778650058836339064832) *
(3201546606177940316018966528, 3201546948253280471426793472)
(3246126368411500102994100224, 3246126753752370852634034176)
(30886958374694867104144818176, 30886959839775761339382759424) *
(58230121837690366602703273984, 58230128772645945195748130816)
(1564092755993481057609717907456, 1564092823984266648474085228544) *
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
T. D. Noe, Sep 25 2010
STATUS
approved