A030494 If n is even, 2(n/2 + 1)! - 1; if n is odd, ((n + 1)/2 + 1)! - 1.

1, 3, 5, 11, 23, 47, 119, 239, 719, 1439, 5039, 10079, 40319, 80639, 362879, 725759, 3628799, 7257599, 39916799, 79833599, 479001599, 958003199, 6227020799, 12454041599, 87178291199, 174356582399, 1307674367999, 2615348735999

Offset

1,2

Links

Table of n, a(n) for n=1..28.

Mathematica

Table[If[EvenQ[n], 2(n/2 + 1)! - 1, ((n + 1)/2 + 1)! - 1], {n, 40}] (* Alonso del Arte, Feb 19 2020 *)

Prog

(PARI) a(n)=if(n%2, (n\2+2)!, (n/2+1)!*2) - 1 \\ Charles R Greathouse IV, Mar 27 2020

Crossrefs

s(n) = s(n + 1), where s = A030298.

Sequence in context: A290114 A032803 A335883 * A246491 A084361 A077229

Adjacent sequences: A030491 A030492 A030493 * A030495 A030496 A030497

Keyword

nonn,easy

Author

Clark Kimberling

Extensions

Better description and more terms from Erich Friedman.

Status

approved