A139464 a(n) = n! + 2n - 1.

2, 5, 11, 31, 129, 731, 5053, 40335, 362897, 3628819, 39916821, 479001623, 6227020825, 87178291227, 1307674368029, 20922789888031, 355687428096033, 6402373705728035, 121645100408832037, 2432902008176640039

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Florian Luca and Igor E. Shparlinski, On the largest prime factor of n! + 2^n - 1, Journal de Theorie des Nombres de Bordeaux 17 (2005), 859-870.

Formula

a(n) = A000142(n) + A005408(n-1).

Maple

A139464:=n->n!+2*n-1: seq(A139464(n), n=1..20); # Wesley Ivan Hurt, Nov 15 2014

Mathematica

Table[n! + 2 n - 1, {n, 40}]

Prog

(PARI) a(n)=n!+2*n-1 \\ Charles R Greathouse IV, Feb 01 2013
(Magma) [Factorial(n)+2*n-1 : n in [1..20]]; // Wesley Ivan Hurt, Nov 15 2014

Crossrefs

Cf. A127986, A127987, A139023, A139024, A139465, A139466, A139467.

Cf. A000142 (n!), A005408 (2n+1).

Sequence in context: A380990 A190865 A275427 * A174537 A101837 A124483

Adjacent sequences: A139461 A139462 A139463 * A139465 A139466 A139467

Keyword

nonn,easy

Author

Artur Jasinski, Apr 22 2008

Status

approved