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A175112 First differences of A175111. 4
1, 120, 1442, 6840, 21122, 51000, 105122, 194040, 330242, 528120, 804002, 1176120, 1664642, 2291640, 3081122, 4059000, 5253122, 6693240, 8411042, 10440120, 12816002, 15576120, 18759842, 22408440, 26565122, 31275000, 36585122 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Convolution of the finite sequence 1,116,967,1672,967,116,1 with A001752. Number of points in the standard root system of the D_5 lattice having L_infinity norm n.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (4,-5,0,5,-4,1).

FORMULA

a(n)= 4*a(n-1) -5*a(n-2) +5*a(n-4) -4*a(n-5) +a(n-6), n>6.

a(n) = ((2*n+1)^5-(2*n-1)^5)/2+(-1)^n, n>0.

G.f.: (116*x+967*x^2+1672*x^3+967*x^4+116*x^5+x^6+1)/((1+x)*(1-x)^5).

MATHEMATICA

CoefficientList[Series[(116*x + 967*x^2 + 1672*x^3 + 967*x^4 + 116*x^5 + x^6+1)/((1 + x)*(1 - x)^5), {x, 0, 40}], x] (* Vincenzo Librandi, Dec 19 2012 *)

PROG

(MAGMA) I:=[1, 120, 1442, 6840, 21122, 51000, 105122]; [n le 7 select I[n] else 4*Self(n-1) - 5*Self(n-2) + 5*Self(n-4) - 4*Self(n-5) + Self(n-6): n in [1..40]]; // Vincenzo Librandi, Dec 19 2012

CROSSREFS

Cf. A110907, A117216, A175114.

Sequence in context: A167549 A052776 A052770 * A257996 A183597 A027795

Adjacent sequences:  A175109 A175110 A175111 * A175113 A175114 A175115

KEYWORD

easy,nonn

AUTHOR

R. J. Mathar, Feb 13 2010

STATUS

approved

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Last modified November 18 01:16 EST 2017. Contains 294837 sequences.