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A226915
Fourth column of A226518.
2
-1, 1, 1, 1, 1, -1, 3, -1, 1, 1, 1, -1, 3, -1, 1, 1, -1, 3, 3, 1, 1, 1, 3, -1, 1, 1, 1, 1, 1, 1, 1, -1, -1, 1, 1, -1, 3, -1, 1, 1, 3, 3, -1, 1, -1, 1, 1, 1, 1, 3, 3, 1, 1, 3, -1, 1, 1, 1, -1, -1, -1, 3, 3, -1, -1, 3, 1, 1, 1, 3, 1, 1, -1, 3, -1, 1, 1, 3, 1, 1, 3, 3, 1, 1, 1, 3, -1, 1, 1, 3, 1, 1, -1, 3, -1, 1
OFFSET
3,7
FORMULA
a(n) = 1 + Legendre(2,p) + Legendre(3,p) where p = prime(n).
CROSSREFS
Cf. A226518.
Sequence in context: A272334 A014491 A214071 * A180173 A318668 A322361
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Jun 22 2013
STATUS
approved