A037082 Primes of the form k!!! + 1.

2, 3, 5, 11, 19, 29, 163, 281, 881, 209441, 264539521, 72642169601, 9927882482918401, 26582634158080001, 141383412854531380076544001, 427380210218181008588800001, 2295148179742698933452800001, 191433282535027132859721811688265047080960000001

Offset: 1

Author

G. L. Honaker, Jr.

Keywords

• nonn

Examples

			11!!! + 1 = 11*8*5*2 + 1 = 881 is prime.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..26
• Index entries for sequences related to factorial numbers.

Crossrefs

Cf. A007661, A037083.

Programs

Mathematica

Select[Table[Times@@Range[n,1,-3]+1,{n,60}],PrimeQ] (* Harvey P. Dale, Jul 09 2014 *)

Formula

a(n) = 1 + A007661(A037083(n+1)). - Elmo R. Oliveira, Feb 22 2025