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A161703
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(4n^3 - 12n^2 + 14n + 3)/3.
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19
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1, 3, 5, 15, 41, 91, 173, 295, 465, 691, 981, 1343, 1785, 2315, 2941, 3671, 4513, 5475, 6565, 7791, 9161, 10683, 12365, 14215, 16241, 18451, 20853, 23455, 26265, 29291, 32541, 36023, 39745, 43715, 47941, 52431, 57193, 62235, 67565, 73191, 79121
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| {a(k): 0 <= k < 4} = divisors of 15:
a(n) = A027750(A006218(14) + k + 1), 0 <= k < A000005(15).
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LINKS
| R. Zumkeller, Enumerations of Divisors
Index to sequences with linear recurrences with constant coefficients, signature (4,-6,4,-1).
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FORMULA
| a(n) = C(n,0) + 2*C(n,1) + 8*C(n,3).
G.f.: (1-x-x^2+9*x^3)/(1-x)^4. [Colin Barker, Jan 08 2012]
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EXAMPLE
| Differences of divisors of 15 to compute the coefficients of their interpolating polynomial, see formula:
1 ... 3 ... 5 ... 15
.. 2 ... 2 .. 10
..... 0 ... 8
........ 8.
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PROG
| (MAGMA)[(4*n^3 - 12*n^2 + 14*n + 3)/3: n in [0..50]]; [From Vincenzo Librandi, Dec 27 2010]
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CROSSREFS
| Cf. A005408, A000124, A016813, A086514, A000125, A058331, A002522, A161701, A161702, A000127, A161704, A161706-A161708, A161710, A080856, A161711-A161713, A161715, A006261.
Sequence in context: A138017 A148503 A145939 * A018551 A103425 A119472
Adjacent sequences: A161700 A161701 A161702 * A161704 A161705 A161706
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KEYWORD
| nonn,easy
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 17 2009
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