Found by David Broadhurst in 2002. Note that zeta(-1)=-1/12. Hence zeta(1-2p) has denominator 12 and prime numerator.
Table of n, a(n) for n=1..7.
Cf. A112548 (n such that the numerator of zeta(1-n) is prime).
Sequence in context: A104213 A178550 A105896 * A111380 A288612 A109775
Adjacent sequences: A112738 A112739 A112740 * A112742 A112743 A112744
T. D. Noe, Sep 28 2005