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A266583
Smallest prime starting a symmetric n-tuple of consecutive primes of the smallest span (=A266676(n)).
4
2, 2, 3, 5, 18713, 5, 12003179, 17, 1480028129, 13, 1542186111157, 41280160361347, 660287401247633, 10421030292115097, 3112462738414697093, 996689250471604163, 258406392900394343851
OFFSET
1,1
COMMENTS
An n-tuple (p(1),...,p(n)) is symmetric if p(k)+p(n+1-k) is the same for all k=1,2,...,n (cf. A175309).
In contrast to A266512, n-tuples here may be singular and give the complete set of residues modulo some prime. For example, for n=3 we have the symmetric 3-tuple: (3,5,7) = (3,3+2,3+4), but there are no other symmetric 3-tuples of the form (p,p+2,p+4), since one of its elements would be divisible by 3.
For any n, a(n) <= n or a(n) = A266512(n).
FORMULA
a(n) = A000040(A266585(n)).
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Max Alekseyev, Jan 01 2016
STATUS
approved