OFFSET
0,2
COMMENTS
FORMULA
Row sums of A130585.
a(n-1) = Sum_{d|n} phi(n/d)*2^(n/d - 1). [Olivier Gérard, Jan 01 2012]
EXAMPLE
a(3) = 19 = sum of row 3 terms of A130585: (4 + 7 + 6 + 2).
MATHEMATICA
Table[Plus@@Map[Function[d, EulerPhi[(n+1)/d] 2^((n+1)/d-1)], Divisors[n+1]], {n, 0, 30}] (* Olivier Gérard, Jan 01 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Gary W. Adamson, Jun 06 2007
EXTENSIONS
More terms from Olivier Gérard, Jan 01 2012
STATUS
approved