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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 (list; graph; refs; listen; history; text; internal format)
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.
LINKS
EXAMPLE
a(2) = 9 = 3*3 since (1+9)/2=5 and (3+3)/2=3.
CROSSREFS
Sequence in context: A125652 A232701 A364495 * A018746 A289070 A053914
KEYWORD
nonn,hard,more
AUTHOR
Hartmut F. W. Hoft, Jan 09 2021
STATUS
approved

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Last modified June 23 15:10 EDT 2024. Contains 373651 sequences. (Running on oeis4.)