|
| |
|
|
A143128
|
|
Sum {k=1..n} k*sigma(k).
|
|
1
| |
|
|
1, 7, 19, 47, 77, 149, 205, 325, 442, 622, 754, 1090, 1272, 1608, 1968, 2464, 2770, 3472, 3852, 4692, 5364, 6156, 6708, 8148, 8923, 10015, 11095, 12663, 13533, 15693, 16685, 18701, 20285, 22121, 23801, 27077, 28483, 30763, 32947, 36547
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
FORMULA
| Sum {k=1..n} k*sigma(k), where sigma(n) = A000203: (1, 3, 4, 7, 6, 12,...) and n*sigma(n) = A064987: (1, 6, 12, 28,...). Equals row sums of triangle A110662. - Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 12 2008
|
|
|
EXAMPLE
| a(4) = 47 = (1 + 6 + 12 + 28) where A064987 = (1, 6, 12, 28, 30,...).
a(4) = 47 = sum of row 4 terms of triangle A110662 = (15 + 14 + 11 + 7).
|
|
|
MAPLE
| with(numtheory): a:=proc(n) options operator, arrow: sum(k*sigma(k), k=1..n) end proc: seq(a(n), n=1..40); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 12 2008
|
|
|
CROSSREFS
| Cf. A000203, A064987, A110662.
Sequence in context: A155399 A155415 A155273 * A139865 A146403 A000491
Adjacent sequences: A143125 A143126 A143127 * A143129 A143130 A143131
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Gary W. Adamson (qntmpkt(AT)yahoo.com), Jul 26 2008
|
|
|
EXTENSIONS
| Corrected and extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 12 2008
|
| |
|
|
