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 A261809 #25 Sep 08 2022 08:46:13
%S A261809 -1,-1,1,17,109,707,5023,40301,362857,3628771,39916769,479001563,
%T A261809 6227020759,87178291157,1307674367953,20922789887947,355687428095941,
%U A261809 6402373705727939,121645100408831933,2432902008176639929,51090942171709439927,1124000727777607679921
%N A261809 a(n) = n! - prime(n).
%H A261809 G. C. Greubel, <a href="/A261809/b261809.txt">Table of n, a(n) for n = 1..85</a>
%F A261809 a(n) = A000142(n) - A000040(n).
%e A261809 For n=4, a(4) = 4! - prime(4) = 24 - 7 = 17.
%t A261809 Table[n! - Prime[n], {n,1,150}] (* _G. C. Greubel_, Sep 01 2015 *)
%o A261809 (PARI) vector(50, n, n!-prime(n))
%o A261809 (Magma) [Factorial(n)-NthPrime(n): n in [1..30]]; // _Vincenzo Librandi_, Sep 02 2015
%Y A261809 Cf. A000040, A000142, A121926.
%K A261809 sign,easy
%O A261809 1,4
%A A261809 _Altug Alkan_, Sep 01 2015