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 A161706 a(n) = (-11*n^5 + 145*n^4 - 635*n^3 + 1115*n^2 - 494*n + 120)/120. 21
 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 G. C. Greubel, Table of n, a(n) for n = 0..1000 Reinhard Zumkeller, Enumerations of Divisors Index entries for 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 MAPLE A161706:=n->(-11*n^5 + 145*n^4 - 635*n^3 + 1115*n^2 - 494*n + 120)/120: seq(A161706(n), n=0..50); # Wesley Ivan Hurt, Jul 16 2017 MATHEMATICA CoefficientList[Series[(1 - 4*x + 7*x^2 - 9*x^3 + 15*x^4 - 21*x^5)/(1 - x)^6, {x, 0, 50}], x] (* G. C. Greubel, Jul 16 2017 *) PROG (Magma) [(-11*n^5 + 145*n^4 - 635*n^3 + 1115*n^2 - 494*n + 120)/120: n in [0..50]]; // Vincenzo Librandi, Dec 27 2010 (PARI) a(n)=(-11*n^5+145*n^4-635*n^3+1115*n^2-494*n+120)/120 \\ Charles R Greathouse IV, Sep 24 2015 (Python) def A161706(n): return (n*(n*(n*(n*(145 - 11*n) - 635) + 1115) - 494) + 120)//15>>3 # Chai Wah Wu, Oct 23 2023 CROSSREFS Cf. A005408, A000124, A016813, A086514, A000125, A058331, A002522, A161701, A161702, A161703, A000127, A161704, A161707, A161708, A161710, A080856, A161711, A161712, A161713, A161715, A006261. Cf. A005018, A161700, A161856. - Reinhard Zumkeller, Jun 21 2009 Sequence in context: A005018 A249399 A118551 * A128401 A018467 A035524 Adjacent sequences: A161703 A161704 A161705 * A161707 A161708 A161709 KEYWORD sign,easy AUTHOR Reinhard Zumkeller, Jun 17 2009 STATUS approved

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Last modified May 19 03:29 EDT 2024. Contains 372666 sequences. (Running on oeis4.)