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 A177771 #24 Mar 29 2025 15:31:20 %S A177771 1,2,24,720,3628800,479001600,20922789888000,6402373705728000, %T A177771 1124000727777607680000,304888344611713860501504000000, %U A177771 265252859812191058636308480000000 %N A177771 a(n) = (prime(n) - 1)!. %C A177771 By Wilson's theorem, a(n) = -1 (mod p) where p is the n-th prime. - _Charles R Greathouse IV_, Sep 04 2013 %D A177771 Paulo Ribenboim, The Little Book of Bigger Primes, Springer-Verlag NY 2004. See p. 21. %H A177771 Vincenzo Librandi, <a href="/A177771/b177771.txt">Table of n, a(n) for n = 1..80</a> %F A177771 a(n) = A010050(A005097(n-1)). a(n)^2 = A177926(n). - _R. J. Mathar_, May 24 2010 %t A177771 (Prime[Range[12]]-1)! (* _Harvey P. Dale_, Jul 12 2011 *) %o A177771 (Magma) [Factorial(p-1): p in PrimesUpTo(20)]; // _Vincenzo Librandi_, May 31 2013 %o A177771 (PARI) apply(p->(p-1)!,primes(10)) \\ _Charles R Greathouse IV_, Sep 04 2013 %Y A177771 Cf. A006093, A039716. %K A177771 nonn %O A177771 1,2 %A A177771 _Giovanni Teofilatto_, May 13 2010