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A340483
a(n) is the smallest product of n (not necessarily distinct) odd primes m = p_1*p_2*...*p_n such that (d+m/d)/2 is a prime for all d dividing m.
0
3, 9, 105, 1365, 884037
OFFSET
1,1
COMMENTS
This sequence differs from A128281 only in the value A128281(2)=21: a(2)=9 since, for n=2 only, the specification "distinct primes" makes a difference.
EXAMPLE
a(2) = 9 = 3*3 since (1+9)/2=5 and (3+3)/2=3.
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Hartmut F. W. Hoft, Jan 09 2021
STATUS
approved