A082459 Multiply by 1, add 1, multiply by 2, add 2, etc.

-1, -1, 0, 0, 2, 6, 9, 36, 40, 200, 205, 1230, 1236, 8652, 8659, 69272, 69280, 623520, 623529, 6235290, 6235300, 68588300, 68588311, 823059732, 823059744, 10699776672, 10699776685, 149796873590, 149796873604, 2246953104060, 2246953104075, 35951249665200, 35951249665216

Offset: 0

Author

Vladeta Jovovic, Apr 25 2003

Keywords

• sign

Comments

Bisections: A038156 and A038157.

Links

• Robert Israel, Table of n, a(n) for n = 0..898

Crossrefs

Cf. A019464 - A019466.

Programs

Maple

seq(op(simplify([exp(1)*GAMMA(k+1,1)-k!-1, exp(1)*GAMMA(k+2,1)-(k+1)!-k-2])),k=0..20); # Robert Israel, Jan 11 2018

Mathematica

FoldList[If[OddQ@ #2, #1 ((#2 + 1)/2), #1 + #2/2] &, -1, Range@ 31] (* Michael De Vlieger, Jan 11 2018 *)

Formula

From Robert Israel, Jan 11 2018: (Start)

a(2*k) = e*Gamma(k+1,1) - k! - 1.

a(2*k+1) = e*Gamma(k+2,1) - (k+1)! - k - 2. (End)