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a(n) = Product_{k=1..4*n-9} prime(k) - prime(4n)^4 where prime(i) = i-th prime.
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%I #12 Jun 19 2018 05:12:51

%S -1874131,-7379971,200535078449,614889782525749169,

%T 7858321551080266924799489,267064515689275851355623723492869,

%U 23984823528925228172706521638691738510609,4014476939333036189094441199026045136644989502689,1492182350939279320058875736615841068547583863325477042409

%N a(n) = Product_{k=1..4*n-9} prime(k) - prime(4n)^4 where prime(i) = i-th prime.

%C It is known that a(n) > 0 for n >= 5.

%H Harry J. Smith, <a href="/A064820/b064820.txt">Table of n, a(n) for n = 3..50</a>

%H S. E. Mamangakis, <a href="https://doi.org/10.1215/S0012-7094-62-02946-0">Synthetic proof of some prime number inequalities</a>, Duke Math. J., 29 (1962), 471-473.

%o (PARI) { for (n=3, 50, p=prod(k=1, 4*n-9, prime(k)); write("b064820.txt", n, " ", p - prime(4*n)^4) ) } \\ _Harry J. Smith_, Sep 27 2009

%K sign

%O 3,1

%A _N. J. A. Sloane_, Oct 23 2001