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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 Table of n, a(n) for n=1..5. EXAMPLE a(2) = 9 = 3*3 since (1+9)/2=5 and (3+3)/2=3. CROSSREFS Cf. A128281, A128283, A340482. Sequence in context: A125652 A232701 A364495 * A018746 A289070 A053914 Adjacent sequences: A340480 A340481 A340482 * A340484 A340485 A340486 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.)