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 A139057 #20 Jun 09 2025 00:52:55
%S A139057 7,239,159667199,6974263295999,2947253997913233984847871999999,
%T A139057 98410933013201380282539536547839999999,
%U A139057 20138421021124611879118377356171332502421503999999999
%N A139057 Primes of the form (k!-3)/3.
%C A139057 Numbers k for which (k! - 3)/3 is prime see A139056.
%C A139057 a(8) is 180 decimal digits long. See formula for more terms. - _Derek Orr_, Mar 28 2014
%F A139057 a(n) = (A139056(n)!-3)/3 for all n. - _Derek Orr_, Mar 28 2014
%t A139057 a = {}; Do[If[PrimeQ[(-3 + n!)/3], AppendTo[a, (-3 + n!)/3]], {n, 1, 100}]; a
%t A139057 Select[(Range[50]!-3)/3,PrimeQ] (* _Harvey P. Dale_, Nov 27 2015 *)
%o A139057 (PARI) for(n=1,1000,if(floor(n!/3-1)==n!/3-1,if(ispseudoprime(n!/3-1),print(n!/3-1)))) \\ _Derek Orr_, Mar 28 2014
%Y A139057 Cf. A089085, A117141, A007749, A139056.
%K A139057 nonn
%O A139057 1,1
%A A139057 _Artur Jasinski_, Apr 07 2008
%E A139057 Definition corrected by _Derek Orr_, Mar 28 2014