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.
%I A103855 #22 Aug 11 2025 13:42:04
%S A103855 1,1,91,4831,39914491,6226990771,355687427585491,121645100399132311,
%T A103855 25852016738884753547131,8841761993739701954537146306771,
%U A103855 8222838654177922817725362319509871,13763753091226345046315979581573481661865191,33452526613163807108170062053440751360901736472791
%N A103855 a(n) = prime(n)! - prime(n)# + 1.
%H A103855 G. C. Greubel, <a href="/A103855/b103855.txt">Table of n, a(n) for n = 1..86</a>
%H A103855 Reinhard Zumkeller, <a href="/A103855/a103855.txt">p(n)! - p(n)# + 1</a>.
%F A103855 a(n) = A039716(n) - A002110(n) + 1 = A002110(n) * (A092435(n) - 1) + 1.
%t A103855 primorial[n_] := Product[Prime[i], {i, n}]; A103855[n_] := Prime[n]! - primorial[n] + 1; Array[A103855, 20] (* _G. C. Greubel_, May 09 2017 *)
%t A103855 With[{nn=15},#[[1]]-#[[2]]+1&/@Thread[{Prime[Range[nn]]!,FoldList[Times,Prime[Range[nn]]]}]] (* _Harvey P. Dale_, Aug 11 2025 *)
%Y A103855 Cf. A103856, A103857, A103858, A103859, A103860, A103861, A103890.
%Y A103855 Cf. A002110, A039716, A092435.
%K A103855 nonn
%O A103855 1,3
%A A103855 _Reinhard Zumkeller_, Feb 20 2005