A176362 a(n) = sigma(n*2^(n-1)).

1, 7, 28, 63, 186, 508, 1016, 2047, 6643, 12282, 24564, 65532, 114674, 262136, 786408, 1048575, 2359278, 6815731, 10485740, 25165818, 67108832, 100663284, 201326568, 536870908, 1040187361, 1879048178, 5368709080, 8589934584

Offset

1,2

Links

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

Formula

Logarithmic derivative of A176361.

Mathematica

Table[DivisorSigma[1, n 2^(n-1)], {n, 40}]  (* Harvey P. Dale, Mar 11 2011 *)

Prog

(PARI) a(n)=sigma(n*2^(n-1))

Crossrefs

Cf. A176361, A176311, A000203 (sigma).

Sequence in context: A024844 A230285 A033582 * A358999 A008457 A138503

Adjacent sequences: A176359 A176360 A176361 * A176363 A176364 A176365

Keyword

nonn

Author

Paul D. Hanna, Apr 15 2010

Status

approved