

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




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



KEYWORD

nonn,hard,more


AUTHOR



STATUS

approved



