

A266676


Smallest span (difference between the start and end) of a symmetric ntuple of consecutive primes.


3



0, 1, 4, 8, 36, 14, 60, 26, 84, 34, 132, 46, 168, 56, 180, 74, 240, 82
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OFFSET

1,3


COMMENTS

An ntuple (p(1),...,p(n)) is symmetric if p(k)+p(n+1k) is the same for all k=1,2,...,n (cf. A175309).
In contrast to A266511, ntuples here may be singular and give the complete set of residues modulo some prime. For example, for n=3 we have the symmetric 3tuple: (3,5,7) = (3,3+2,3+4) of span a(3)=4, but there are no other symmetric 3tuples of the form (p,p+2,p+4), since one of its elements would be divisible by 3.
a(n) <= A266511(n).


LINKS

Table of n, a(n) for n=1..18.


CROSSREFS

The smallest starting primes and their indices of the corresponding tuples are given in A266583 and A266585.
Cf. A055380, A065688, A175309, A266511, A266512, A261324.
Sequence in context: A218628 A149108 A149109 * A046056 A158863 A074736
Adjacent sequences: A266673 A266674 A266675 * A266677 A266678 A266679


KEYWORD

nonn,more


AUTHOR

Max Alekseyev, Jan 02 2016


STATUS

approved



