OFFSET
1,1
COMMENTS
It is known that a(n) > 0 for n >= 4.
REFERENCES
D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, Section VII.18, p. 493.
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..100
S. E. Mamangakis, Synthetic proof of some prime number inequalities, Duke Math. J., 29 (1962), 471-473.
PROG
(PARI) a(n) = prod(k=1, n, prime(k)) - prime(4*n); \\ Michel Marcus, Jun 19 2018
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Oct 16 2001
STATUS
approved