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A161711 a(n) = (-4*n^3 + 27*n^2 - 20*n + 3)/3. 18
1, 2, 13, 26, 33, 26, -3, -62, -159, -302, -499, -758, -1087, -1494, -1987, -2574, -3263, -4062, -4979, -6022, -7199, -8518, -9987, -11614, -13407, -15374, -17523, -19862, -22399, -25142, -28099, -31278, -34687, -38334, -42227, -46374, -50783 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
{a(k): 0 <= k < 4} = divisors of 26:
a(n) = A027750(A006218(25) + k + 1), 0 <= k < A000005(26).
LINKS
FORMULA
a(n) = C(n,0) + C(n,1) + 10*C(n,2) - 8*C(n,3).
G.f.: (1-2*x+11*x^2-18*x^3)/(1-x)^4. - Bruno Berselli, Jul 17 2011
EXAMPLE
Differences of divisors of 26 to compute the coefficients of their interpolating polynomial, see formula:
1 2 13 26
1 11 13
10 2
-8
MATHEMATICA
LinearRecurrence[{4, -6, 4, -1}, {1, 2, 13, 26}, 40] (* Harvey P. Dale, Jul 02 2017 *)
PROG
(Magma) [(-4*n^3 + 27*n^2 - 20*n + 3)/3: n in [0..40]]; // Vincenzo Librandi, Jul 17 2011
(PARI) x='x+O('x^50); Vec((1-2*x+11*x^2-18*x^3)/(1-x)^4) \\ G. C. Greubel, Jul 16 2017
CROSSREFS
Sequence in context: A329630 A018628 A018657 * A018745 A117983 A367265
KEYWORD
sign,easy
AUTHOR
Reinhard Zumkeller, Jun 17 2009
STATUS
approved

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Last modified June 17 07:09 EDT 2024. Contains 373433 sequences. (Running on oeis4.)