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Table of n, a(n) for n=0..24.
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)
Cf. A000031, A100446. Equals 2*A026119.
Sequence in context: A000116 A302862 A006407 * A241891 A112278 A059731
Adjacent sequences: A100444 A100445 A100446 * A100448 A100449 A100450
N. J. A. Sloane, Nov 21 2004
More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 19 2005