A240804 a(n) = -2 + product of first n odd primes.

1, 13, 103, 1153, 15013, 255253, 4849843, 111546433, 3234846613, 100280245063, 3710369067403, 152125131763603, 6541380665835013, 307444891294245703, 16294579238595022363, 961380175077106319533, 58644190679703485491633, 3929160775540133527939543, 278970415063349480483707693

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Des MacHale, Infinitely many proofs that there are infinitely many primes, Math. Gazette, 97 (No. 540, 2013), 495-498.

Formula

a(n) = A070826(n+1)-2. - R. J. Mathar, May 03 2017

Mathematica

Table[Product[Prime[k + 1], {k, 1, n}] - 2, {n, 1, 40}] (* Vincenzo Librandi, Apr 15 2014 *)
Rest[FoldList[Times, 1, Prime[Range[2, 20]]]]-2 (* Harvey P. Dale, Mar 17 2015 *)

Prog

(Magma) [-2+&*[NthPrime(i+1): i in [1..n]]: n in [1..20]]; // Vincenzo Librandi, Apr 15 2014

Crossrefs

Cf. A000945, A000946, A005265, A005266, A240803.

Sequence in context: A220734 A268991 A216179 * A100277 A087398 A080440

Adjacent sequences: A240801 A240802 A240803 * A240805 A240806 A240807

Keyword

nonn,easy

Author

N. J. A. Sloane, Apr 14 2014

Status

approved