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.
f[n_] := Product[ Prime[i], {i, 2, n, 2}] + Product[ Prime[i], {i, 1, n, 2}]; f[1] = 2; Do[ If[ PrimeQ[ f[n]], Print[n]], {n, 2060}]
PrimeFactors[n_] := Flatten[ Table[ #[[1]], {1} ] & /@ FactorInteger[n]]; f[n_] := Product[ Prime[i], {i, 2, n, 2}] + Product[ Prime[i], {i, 1, n, 2}]; f[1] = 2; Table[ Length[ PrimeFactors[ f[n]]], {n, 80}]
a(5) = 2*5*11 - 3*7 = 89, a(6) = 3*7*13 - 2*5*11 = 163; a(7) = 2*5*11*17 - 3*7*13 = 1597, a(8) = 3*7*13*19 - 2*5*11*17 = 3317.
PrimeFactors[n_] := Flatten[ Table[ #[[1]], {1} ] & /@ FactorInteger[n]]; f[n_] := Abs[ Product[ Prime[i], {i, 2, n, 2}] + Product[ Prime[i], {i, 1, n, 2}]]; f[1] = 2; Table[ f[n], {n, 24}]
Join[{2},Table[Abs[Times@@Prime[Range[1,Floor[n/2],2]]-Times@@Prime[Range[ 2,Floor[ n/2 ],2]]],{n,4,45,2}]] (* Harvey P. Dale, Jan 11 2023 *)