A176311 a(n) = sigma(n*2^n).

3, 15, 60, 127, 378, 1020, 2040, 4095, 13299, 24570, 49140, 131068, 229362, 524280, 1572840, 2097151, 4718574, 13631475, 20971500, 50331642, 134217696, 201326580, 402653160, 1073741820, 2080374753, 3758096370, 10737418200, 17179869176

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Formula

Logarithmic derivative of A176310.

Maple

with(numtheory): seq( sigma(n*2^n), n=1..30); # G. C. Greubel, Nov 26 2019

Mathematica

Table[DivisorSigma[1, n*2^n], {n, 30}] (* Harvey P. Dale, Mar 05 2015 *)

Prog

(PARI) a(n)=sigma(n*2^n)
(Magma) [DivisorSigma(1, n*2^n): n in [1..30]]; // G. C. Greubel, Nov 26 2019
(Sage) [sigma(n*2^n, 1) for n in (1..30)] # G. C. Greubel, Nov 26 2019
(GAP) List([1..30], n-> Sigma(n*2^n)); # G. C. Greubel, Nov 26 2019

Crossrefs

Cf. A176310, A000203 (sigma).

Sequence in context: A328104 A179604 A128237 * A036750 A286183 A058748

Adjacent sequences: A176308 A176309 A176310 * A176312 A176313 A176314

Keyword

nonn

Author

Paul D. Hanna, Apr 15 2010

Status

approved