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

%I #20 Sep 08 2022 08:46:07

%S 1,13,103,1153,15013,255253,4849843,111546433,3234846613,100280245063,

%T 3710369067403,152125131763603,6541380665835013,307444891294245703,

%U 16294579238595022363,961380175077106319533,58644190679703485491633,3929160775540133527939543,278970415063349480483707693

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

%H Vincenzo Librandi, <a href="/A240804/b240804.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.

%F a(n) = A070826(n+1)-2. - _R. J. Mathar_, May 03 2017

%t Table[Product[Prime[k + 1], {k, 1, n}] - 2, {n, 1, 40}] (* _Vincenzo Librandi_, Apr 15 2014 *)

%t Rest[FoldList[Times,1,Prime[Range[2,20]]]]-2 (* _Harvey P. Dale_, Mar 17 2015 *)

%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, A240803.

%K nonn,easy

%O 1,2

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