|
|
A274536
|
|
a(n) = 6 * sigma(n).
|
|
11
|
|
|
6, 18, 24, 42, 36, 72, 48, 90, 78, 108, 72, 168, 84, 144, 144, 186, 108, 234, 120, 252, 192, 216, 144, 360, 186, 252, 240, 336, 180, 432, 192, 378, 288, 324, 288, 546, 228, 360, 336, 540, 252, 576, 264, 504, 468, 432, 288, 744, 342, 558, 432, 588, 324, 720, 432, 720, 480, 540, 360, 1008, 372, 576, 624, 762
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
6 times the sum of the divisors of n.
a(n) is also the total number of horizontal rhombuses in the terraces of the n-th level of an irregular stepped pyramid (starting from the top) in which the structure of every 60-degree-three-dimensional sector arises after the 60-degree-zig-zag folding of every row of the diagram of the isosceles triangle A237593. The top of the pyramid is a six-pointed star formed by six rhombuses (see Links section).
|
|
LINKS
|
|
|
FORMULA
|
Conjecture: a(n) = sigma(5*n) = A283118(n) iff n is not a multiple of 5. - Omar E. Pol, Oct 02 2018
|
|
MAPLE
|
with(numtheory): seq(6*sigma(n), n=1..64);
|
|
MATHEMATICA
|
|
|
PROG
|
(PARI) a(n) = 6 * sigma(n);
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|