|
| |
|
|
A135539
|
|
Triangle read by rows: T(n,k) = number of divisors of n that are >= k.
|
|
3
|
|
|
|
1, 2, 1, 2, 1, 1, 3, 2, 1, 1, 2, 1, 1, 1, 1, 4, 3, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 4, 3, 2, 2, 1, 1, 1, 1, 3, 2, 2, 1, 1, 1, 1, 1, 1, 4, 3, 2, 2, 2, 1, 1, 1, 1, 1
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
COMMENTS
|
Previous definition was "A051731 * A000012".
Row sums = sigma(n), A000203: (1, 3, 4, 7, 6, 12, 8, 15,...). Left border = d(n), A000005: (1, 2, 2, 3, 2, 4, 2,...).
|
|
|
LINKS
|
Table of n, a(n) for n=1..55.
|
|
|
FORMULA
|
A051731 * A000012. Triangle read by rows, partial sums of A051731 starting from the right.
|
|
|
EXAMPLE
|
First few rows of the triangle are:
[1]
[2, 1]
[2, 1, 1]
[3, 2, 1, 1]
[2, 1, 1, 1, 1]
[4, 3, 2, 1, 1, 1]
[2, 1, 1, 1, 1, 1, 1]
[4, 3, 2, 2, 1, 1, 1, 1]
[3, 2, 2, 1, 1, 1, 1, 1, 1]
[4, 3, 2, 2, 2, 1, 1, 1, 1, 1]
[2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
[6, 5, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1]
...
|
|
|
MAPLE
|
with(numtheory);
f1:=proc(n) local d, s1, t1, t2, i;
d:=tau(n);
s1:=sort(divisors(n));
t1:=Array(1..n, 0);
for i from 1 to d do t1[n-s1[i]+1]:=1; od:
t2:=PSUM(convert(t1, list));
[seq(t2[n+1-i], i=1..n)];
end proc;
for n from 1 to 15 do lprint(f1(n)); od: # N. J. A. Sloane, Nov 09 2018
|
|
|
CROSSREFS
|
Cf. A051731, A000203, A000005.
Sequence in context: A146290 A347045 A323345 * A240060 A129264 A135840
Adjacent sequences: A135536 A135537 A135538 * A135540 A135541 A135542
|
|
|
KEYWORD
|
nonn,tabl
|
|
|
AUTHOR
|
Gary W. Adamson, Oct 30 2007
|
|
|
EXTENSIONS
|
Clearer definition from N. J. A. Sloane, Nov 09 2018
|
|
|
STATUS
|
approved
|
| |
|
|
