|
| |
|
|
A161706
|
|
(-11*n^5 + 145*n^4 - 635*n^3 + 1115*n^2 - 494*n + 120)/120.
|
|
20
|
|
|
|
1, 2, 4, 5, 10, 20, 21, -27, -201, -626, -1486, -3035, -5608, -9632, -15637, -24267, -36291, -52614, -74288, -102523, -138698, -184372, -241295, -311419, -396909, -500154, -623778, -770651, -943900, -1146920, -1383385, -1657259, -1972807
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,2
|
|
|
COMMENTS
|
{a(k): 0 <= k < 6} = divisors of 20:
a(n) = A027750(A006218(19) + k + 1), 0 <= k < A000005(20).
|
|
|
LINKS
|
Table of n, a(n) for n=0..32.
R. Zumkeller, Enumerations of Divisors
Index to sequences with linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).
|
|
|
FORMULA
|
a(n) = C(n,0) + C(n,1) + C(n,2) - 2*C(n,3) + 7*C(n,4) - 11*C(n,5).
G.f.: (1-4*x+7*x^2-9*x^3+15*x^4-21*x^5)/(1-x)^6. [Colin Barker, Apr 25 2012]
|
|
|
EXAMPLE
|
Differences of divisors of 20 to compute the coefficients of their interpolating polynomial, see formula:
1 ... 2 ... 4 ... 5 ... 10 ... 20
.. 1 ... 2 ... 1 ... 5 ... 10
..... 1 .. -1 ... 4 ... 5
....... -2 ... 5 ... 1
........... 7 .. -4
............ -11.
|
|
|
PROG
|
(MAGMA)[(-11*n^5 + 145*n^4 - 635*n^3 + 1115*n^2 - 494*n + 120)/120: n in [0..50]]; [From Vincenzo Librandi, Dec 27 2010]
|
|
|
CROSSREFS
|
A005408, A000124, A016813, A086514, A000125, A058331, A002522, A161701, A161702, A161703, A000127, A161704, A161707, A161708, A161710, A080856, A161711, A161712, A161713, A161715, A006261.
A005018, A161700, A161856. [From Reinhard Zumkeller, Jun 21 2009]
Sequence in context: A000675 A005018 A118551 * A128401 A018467 A035524
Adjacent sequences: A161703 A161704 A161705 * A161707 A161708 A161709
|
|
|
KEYWORD
|
sign,easy
|
|
|
AUTHOR
|
Reinhard Zumkeller, Jun 17 2009
|
|
|
STATUS
|
approved
|
| |
|
|
