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a(n) = 2 + product of first n odd primes.
2

%I #16 Sep 08 2022 08:46:07

%S 5,17,107,1157,15017,255257,4849847,111546437,3234846617,100280245067,

%T 3710369067407,152125131763607,6541380665835017,307444891294245707,

%U 16294579238595022367,961380175077106319537,58644190679703485491637,3929160775540133527939547,278970415063349480483707697

%N a(n) = 2 + product of first n odd primes.

%H Vincenzo Librandi, <a href="/A240803/b240803.txt">Table of n, a(n) for n = 1..200</a>

%H Des MacHale, <a href="http://dx.doi.org/10.2307/3621650">Infinitely many proofs that there are infinitely many primes</a>, Math. Gazette, 97 (No. 540, 2013), 495-498.

%t Table[Product[Prime[k + 1], {k, 1, n}] + 2, {n, 1, 30}] (* _Vincenzo Librandi_, Apr 15 2014 *)

%o (Magma) [2+&*[NthPrime(i+1): i in [1..n]]: n in [1..20]]; // _Vincenzo Librandi_, Apr 15 2014

%Y Cf. A000945, A000946, A005265, A005266, A240804.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Apr 14 2014