This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
Select[Range[65], PrimeQ[Product[Product[Prime[i],{i,1,n}],{n,1,#}]-1]&] (* Stefan Steinerberger, Apr 12 2006 *)
a(3)=361 since 361 = (2)*(2*3)*(2*3*5) + 1.
Table[Times@@Table[Times@@Prime[Range[n]],{n,k}]+1,{k,40}] (* Jayanta Basu, May 12 2013 *)
Rest[FoldList[Times,1,Rest[FoldList[Times,1,Prime[Range[10]]]]]]+1 (* Harvey P. Dale, Sep 16 2013 *)
a(n) = 1 + prod(k=1, n, prime(k)^(n-k+1)) \\ Andrew Howroyd, Dec 10 2024
a(3) = (2)*(2*3)*(2*3*5) - 1 = 359.
Table[Times@@Table[Times@@Prime[Range[n]],{n,k}]-1,{k,40}]
(* or *)
pr2=1; Table[pr1=1; Do[pr1=pr1*Prime[n],{n,k}]; pr2=pr2*pr1; pr2-1,{k,40}] (* Jayanta Basu, May 12 2013 *)
a(n) = -1 + prod(k=1, n, prime(k)^(n-k+1)) \\ Andrew Howroyd, Dec 10 2024
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