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 A212760 Number of (w,x,y,z) with all terms in {0,...,n}, w even, and x = y + z. 5
 1, 3, 12, 20, 45, 63, 112, 144, 225, 275, 396, 468, 637, 735, 960, 1088, 1377, 1539, 1900, 2100, 2541, 2783, 3312, 3600, 4225, 4563, 5292, 5684, 6525, 6975, 7936, 8448, 9537, 10115, 11340, 11988, 13357, 14079, 15600, 16400, 18081, 18963, 20812, 21780, 23805 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS A signed version is A122576. For a guide to related sequences, see A211795. Partial sums of the positive elements of A129194. - Omar E. Pol, Dec 28 2013 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (1,3,-3,-3,3,1,-1). FORMULA a(n) = a(n-1)+3*a(n-2)-3*a(n-3)-3*a(n-4)+3*a(n-5)+a(n-6)-a(n-7). G.f.: ( 1+2*x+6*x^2+2*x^3+x^4 ) / ( (1+x)^3*(1-x)^4 ). a(n) = (n+1)*(n+2)*(2*n+3+(-1)^n)/8. - Wesley Ivan Hurt, Jul 22 2014 a(n) = A260706(A001318(n+1). - Reinhard Zumkeller, Nov 17 2015 a(n) = Sum_{i=1..n+1} numerator(i^2/2). - Wesley Ivan Hurt, Feb 26 2017 MAPLE A212760:=n->(n+1)*(n+2)*(2*n+3+(-1)^n)/8: seq(A212760(n), n=0..50); # Wesley Ivan Hurt, Jul 22 2014 MATHEMATICA t = Compile[{{n, _Integer}}, Module[{s = 0}, (Do[If[(Mod[w, 2] == 0) && x == y + z, s++], {w, 0, n}, {x, 0, n}, {y, 0, n}, {z, 0, n}]; s)]]; Map[t[#] &, Range[0, 50]]  (* A212760 *) Table[(n + 1) (n + 2) (2 n + 3 + (-1)^n)/8, {n, 0, 50}] (* Wesley Ivan Hurt, Jul 22 2014 *) CoefficientList[Series[(1 + 2 x + 6 x^2 + 2 x^3 + x^4)/((1 + x)^3 (1 - x)^4), {x, 0, 40}], x] (* Vincenzo Librandi, Jul 23 2014 *) PROG (MAGMA) [(n+1)*(n+2)*(2*n+3+(-1)^n)/8 : n in [0..50]]; // Wesley Ivan Hurt, Jul 22 2014 (Haskell) a212760 = a260706 . fromInteger . a001318 . (+ 1) -- Reinhard Zumkeller, Nov 17 2015 CROSSREFS Cf. A211795. Cf. A001318, A260706. Sequence in context: A281813 A063102 A122576 * A143268 A193558 A256131 Adjacent sequences:  A212757 A212758 A212759 * A212761 A212762 A212763 KEYWORD nonn,easy AUTHOR Clark Kimberling, May 29 2012 STATUS approved

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Last modified October 17 08:36 EDT 2019. Contains 328107 sequences. (Running on oeis4.)