A064946 a(n) = Sum_{i|n, j|n, j>i} j.

0, 2, 3, 10, 5, 26, 7, 34, 21, 42, 11, 104, 13, 58, 58, 98, 17, 152, 19, 165, 80, 90, 23, 324, 55, 106, 102, 227, 29, 397, 31, 258, 124, 138, 124, 575, 37, 154, 146, 507, 41, 544, 43, 351, 325, 186, 47, 892, 105, 392, 190, 413, 53, 692, 192, 693, 212, 234, 59

Offset

1,2

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Formula

a(n) = Sum_{i=1..tau(n)} (i-1)*d_i, where {d_i}, i=1..tau(n), is increasing sequence of divisors of n.

Example

a(6) = dot_product(0,1,2,3)*(1,2,3,6) = 0*1 + 1*2 + 2*3 + 3*6 = 26.

Maple

with(numtheory): seq(add((i-1)*sort(convert(divisors(n), 'list'))[i], i=1..tau(n)), n=1..200);

Prog

(PARI) { for (n=1, 1000, d=divisors(n); a=sum(i=2, length(d), (i - 1)*d[i]); write("b064946.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 01 2009

Crossrefs

Cf. A000005, A000203.

Sequence in context: A344457 A175899 A328613 * A078730 A334628 A292239

Adjacent sequences: A064943 A064944 A064945 * A064947 A064948 A064949

Keyword

nonn

Author

Vladeta Jovovic, Oct 28 2001

Status

approved