A087147 -id:A087147 - cp's OEIS frontend

A118913 Primes of the form k! + (k+1)! + 1.

3, 31, 45361, 3991681, 2516506653355019284889240277665777045474566836669417196965412366518489408149127168000000000000001

Offset: 1

Paolo P. Lava and Giorgio Balzarotti, May 25 2006

nonn

The next term has 595 digits. - Harvey P. Dale, May 30 2016

			a(2) = 3! + 4! + 1 = 6 + 24 + 1 = 31.
a(3) = 7! + 8! + 1 = 5040 + 40320 + 1 = 45361.

Indices in A087147. - Dmitry Kamenetsky, Oct 21 2008

P:=proc(n) local i, j; for i from 1 by 1 to n do j:=i!+(i+1)!+1; if isprime(j) then print(j); fi; od; end: P(200);

lst={};Do[p=n!+(n+1)!+1;If[PrimeQ[p],AppendTo[lst,p]],{n,0,5!}];lst (* Vladimir Joseph Stephan Orlovsky, Jan 27 2009 *)
Select[Total[#]+1&/@Partition[Range[0,300]!,2,1],PrimeQ] (* Harvey P. Dale, May 30 2016 *)

for(n=0, 1e3, if(isprime(k=n!+(n+1)!+1), print1(k", "))) \\ Charles R Greathouse IV, Feb 14 2011

First term inserted (because 0! + 1! + 1 = 3 is prime) by Dmitry Kamenetsky, Oct 21 2008

A087146 Numbers k such that k! + (k+1)! - 1 is prime.

Original entry on oeis.org

1, 2, 3, 5, 9, 13, 14, 17, 27, 28, 33, 39, 103, 115, 205, 291, 1431, 1532, 1710, 1937, 3901, 3981, 4682, 6569, 20266, 20662

Offset: 1

Farideh Firoozbakht, Aug 19 2003

nonn

291 is in the sequence and also is in the sequence A087147, thus (291!+292!-1,291!+292!+1) is a twin pair of primes. Any additional terms are greater than 1800 with the next prime having more than 5086 digits.
a(27) > 25000. - Robert Price, Jul 12 2015
a(1)-a(26) give certified primes. - Robert Price, Jul 12 2015

			3 is in the sequence because 3!+4!-1=29 is prime.

H. Dubner, Factorial and primorial primes, J. Rec. Math., 19(No. 3, 1987)

Cf. A087147, A051856, A125174 (corresponding primes).

v={}; Do[If[PrimeQ[n!+(n+1)!-1], v=Append[v, n]; Print[v]], {n, 1800}]; v

One more term from Ryan Propper, Aug 13 2005

a(21)-a(26) from Robert Price, Jul 12 2015

cp's OEIS Frontend

A118913 Primes of the form k! + (k+1)! + 1.

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