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 A161715 a(n) = (50*n^7 - 1197*n^6 + 11333*n^5 - 53655*n^4 + 132125*n^3 - 156828*n^2 + 73212*n + 5040)/5040. 21
 1, 2, 3, 5, 6, 10, 15, 30, 171, 886, 3359, 10143, 26072, 59502, 123931, 240048, 438261, 761754, 1270123, 2043641, 3188202, 4840994, 7176951, 10416034, 14831391, 20758446, 28604967, 38862163, 52116860, 69064806, 90525155, 117456180 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS {a(k): 0 <= k < 8} = divisors of 30: a(n) = A027750(A006218(29) + k + 1), 0 <= k < A000005(30). LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..10000 Reinhard Zumkeller, Enumerations of Divisors Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1). FORMULA a(n) = C(n,0) + C(n,1) + C(n,3) - 3*C(n,4) + 9*C(n,5) - 21*C(n,6) + 50*C(n,7). G.f.: (1-6*x+15*x^2-19*x^3+8*x^4+18*x^5-51*x^6+84*x^7)/(-1+x)^8. - R. J. Mathar, Jun 18 2009 EXAMPLE Differences of divisors of 30 to compute the coefficients of their interpolating polynomial, see formula:   1     2     3     5     6    10    15    30      1     1     2     1     4     5    15         0     1    -1     3     1    10            1    -2     4    -2     9              -3     6    -6    11                  9   -12    17                   -21    29                       50 MATHEMATICA CoefficientList[Series[(1-6*x+15*x^2-19*x^3+8*x^4+18*x^5-51*x^6+84*x^7)/(-1+x)^8, {x, 0, 50}], x] (* G. C. Greubel, Jul 16 2017 *) PROG (MAGMA) [(50*n^7 - 1197*n^6 + 11333*n^5 - 53655*n^4 + 132125*n^3 - 156828*n^2 + 73212*n + 5040)/5040: n in [0..40]]; // Vincenzo Librandi, Jul 17 2011 (Python) A161710_list, m = [1], [50, -321, 864, -1249, 1024, -452, 85, 1] for _ in range(1, 10**2):     for i in range(7):         m[i+1]+= m[i]     A161710_list.append(m[-1]) # Chai Wah Wu, Nov 09 2014 (PARI) x='x+O('x^50); Vec((1 -6*x +15*x^2 -19*x^3 +8*x^4 +18*x^5 -51*x^6 +84*x^7) /(-1+x)^8) \\ G. C. Greubel, Jul 16 2017 CROSSREFS Cf. A000124, A000125, A000127, A002522, A005408, A006261, A016813, A058331, A080856, A086514, A161701, A161702, A161703, A161704, A161706, A161707, A161708, A161710, A161711, A161712, A161713. Cf. A018255, A161700, A161856. - Reinhard Zumkeller, Jun 21 2009 Sequence in context: A018255 A194358 A018727 * A335597 A164523 A227305 Adjacent sequences:  A161712 A161713 A161714 * A161716 A161717 A161718 KEYWORD nonn,easy AUTHOR Reinhard Zumkeller, Jun 17 2009 STATUS approved

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Last modified October 21 12:27 EDT 2020. Contains 337914 sequences. (Running on oeis4.)