A100447 Bisection of A000031.

2, 4, 8, 20, 60, 188, 632, 2192, 7712, 27596, 99880, 364724, 1342184, 4971068, 18512792, 69273668, 260301176, 981706832, 3714566312, 14096303344, 53634713552, 204560302844, 781874936816, 2994414645860, 11488774559636

Offset

0,1

Links

Table of n, a(n) for n=0..24.

Maple

with(numtheory):seq((1/(2*n+1))*add(phi(d)*2^((2*n+1)/d), d=divisors(2*n+1)), n=0..30); (C. Ronaldo)

Crossrefs

Cf. A000031, A100446. Equals 2*A026119.

Sequence in context: A302862 A344490 A006407 * A241891 A112278 A309868

Adjacent sequences: A100444 A100445 A100446 * A100448 A100449 A100450

Keyword

nonn,easy

Author

N. J. A. Sloane, Nov 21 2004

Extensions

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 19 2005

Status

approved