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A161704
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(3*n^5 - 35*n^4 + 145*n^3 - 235*n^2 + 152*n + 30)/30.
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20
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1, 2, 3, 6, 9, 18, 59, 190, 513, 1186, 2435, 4566, 7977, 13170, 20763, 31502, 46273, 66114, 92227, 125990, 168969, 222930, 289851, 371934, 471617, 591586, 734787, 904438, 1104041, 1337394, 1608603, 1922094, 2282625, 2695298, 3165571, 3699270
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| {a(k): 0 <= k < 6} = divisors of 18:
a(n) = A027750(A006218(17) + k + 1), 0 <= k < A000005(18).
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LINKS
| R. Zumkeller, Enumerations of Divisors
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FORMULA
| a(n) = C(n,0) + C(n,1) + 2*C(n,3) - 4*C(n,4) + 12*C(n,5).
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EXAMPLE
| Differences of divisors of 18 to compute the coefficients of their interpolating polynomial, see formula:
1 ... 2 ... 3 ... 6 ... 9 ... 18
.. 1 ... 1 ... 3 ... 3 ... 9
..... 0 ... 2 ... 0 ... 6
........ 2 .. -2 ... 6
.......... -4 ... 8
............. 12.
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PROG
| (MAGMA)[(3*n^5 - 35*n^4 + 145*n^3 - 235*n^2 + 152*n + 30)/30: n in [0..50]]; [From Vincenzo Librandi, Dec 27 2010]
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CROSSREFS
| A005408, A000124, A016813, A086514, A000125, A058331, A002522, A161701, A161702, A161703, A000127, A161706, A161707, A161708, A161710, A080856, A161711, A161712, A161713, A161715, A006261.
A018251, A161700, A161856. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 21 2009]
Sequence in context: A032251 A018679 A018741 * A011962 A060172 A193196
Adjacent sequences: A161701 A161702 A161703 * A161705 A161706 A161707
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 17 2009
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