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A238711
Product of all primes p such that 2n - p is also prime.
6
2, 3, 15, 105, 35, 231, 2145, 5005, 4641, 53295, 1616615, 119301, 21505, 7436429, 21489, 57998985, 3038795305, 4123, 13844919, 10393190665, 12838371, 299859855, 7292509103495, 12023917269, 70691995, 37198413949697, 62483343, 2769282065, 98755025688454681
OFFSET
2,1
COMMENTS
Product of n-th row in triangle A171637;
All terms greater than 3 are odd, composite and squarefree numbers, cf. A024556.
n is prime iff n is a factor of a(n).
Product of the distinct primes in the Goldbach partitions of 2n. - Wesley Ivan Hurt, Sep 29 2020
LINKS
FORMULA
A020639(a(n)) = A020481(n); A006530(a(n)) = A020482(n);
A001221(a(n)) = A035026(n); A008472(a(n)) = A238778(n);
A027748(a(n),k) + A027748(a(n),l+1-k) = 2*n for k=1..l, with l=A001221(a(n)); particulary A020639(a(n))+A006530(a(n)) = 2*n;
a(n) = n^c(n) * Product_{i=1..n-1} (i*(2*n-i))^(c(i)*c(2*n-i)), where c is the prime characteristic (A010051). - Wesley Ivan Hurt, Sep 29 2020
PROG
(Haskell)
a238711 n = product $ filter ((== 1) . a010051') $
map (2 * n -) $ takeWhile (<= 2 * n) a000040_list
CROSSREFS
Cf. A000040, A010051, A238778, subsequence of A056911.
Sequence in context: A177012 A107413 A358119 * A362999 A165657 A091835
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 06 2014
STATUS
approved