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A180330
Smallest amicable number of the form 2^n * p * q for which the larger member of the amicable pair has the same form, where p and q are distinct odd primes.
4
2620, 10744, 66928, 2082464, 7677248, 1750776704, 749380864, 7074650624, 25937232896, 161899964416, 3949032574976, 56691934109696, 162222327218176, 5469697508737024, 21547979005558784, 48336727662002176
OFFSET
2,1
COMMENTS
That is, the amicable pair is (2^n pq, 2^n rs) for odd primes p, q, r, s. See A180331 for the numbers 2^n rs. It is easy to show that the four primes must satisfy the equation (p+1)(q+1) = (r+1)(s+1). These amicable pairs are a subset of the regular type (2,2) pairs, which are cataloged by Pedersen. These amicable pairs can be found by using Herman te Riele's method 2. Amicable pairs of this form are known for 1 < n < 49. Do they exist for all n?
LINKS
CROSSREFS
Sequence in context: A066871 A180650 A245008 * A238921 A156398 A139675
KEYWORD
nonn
AUTHOR
T. D. Noe, Sep 07 2010
STATUS
approved