|
| |
|
|
A140651
|
|
A140579^(-1) * A000290, the squares starting (1, 4, 9, ...).
|
|
1
|
|
|
|
1, 2, 3, 8, 5, 36, 7, 32, 27, 100, 11, 144, 13, 196, 225, 128, 17, 324, 19, 400, 441, 484, 23, 576, 125, 676, 243, 784, 29, 900, 31, 512, 1089, 1156, 1225, 1296, 37, 1444, 1521, 1600, 41, 1764, 43, 1936, 2025, 2116, 47, 2304, 343, 2500, 2601, 2704, 53, 2916, 3025, 3136, 3249, 3364, 59, 3600
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
COMMENTS
|
For n > 1, a(n) = n iff n is prime.
a(n) is n times the least common multiple of the proper divisors of n, a(n) = n*A048671(n). - Peter Luschny, Jun 22 2011
|
|
|
LINKS
|
Table of n, a(n) for n=1..60.
|
|
|
FORMULA
|
A140579^(-1) * (1, 4, 9, 16, 25, ...).
|
|
|
EXAMPLE
|
A140579 = an infinite lower triangular matrix with A014963 in the main diagonal and the rest zeros; where A014963 = (1, 2, 3, 2, 5, 1, 7, ...).
a(5) = 5 = (1/A014963(5)) * 25 = (1/5)*25.
|
|
|
MAPLE
|
A140651 := n -> n*ilcm(op(numtheory[divisors](n) minus {1, n})); seq(A140651(i), i=1..60); # Peter Luschny, Jun 22 2011
|
|
|
CROSSREFS
|
Cf. A140579, A014963.
Sequence in context: A119794 A117987 A091136 * A190997 A184392 A007955
Adjacent sequences: A140648 A140649 A140650 * A140652 A140653 A140654
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
Gary W. Adamson and Mats Granvik, May 20 2008
|
|
|
EXTENSIONS
|
a(15)-a(60) from Peter Luschny, Jun 22 2011
|
|
|
STATUS
|
approved
|
| |
|
|
