|
|
A175532
|
|
a(1) = 1; for n>1, a(n) = smallest number of the form 4k+1 and a(n) > a(n-1) such that the pairwise sums of elements are all semiprimes.
|
|
2
|
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
Or, for i<>j, (a(i)+a(j)/2 are primes.
Starting with a(5)=133 on all terms === 13 mod 20.
Is sequence finite?
|
|
LINKS
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|