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 A191903 Number of compositions of odd natural numbers into 4 parts <=n 3
 0, 8, 40, 128, 312, 648, 1200, 2048, 3280, 5000, 7320, 10368, 14280, 19208, 25312, 32768, 41760, 52488, 65160, 80000, 97240, 117128, 139920, 165888, 195312, 228488, 265720, 307328, 353640, 405000, 461760, 524288, 592960, 668168, 750312 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (4,-5,0,5,-4,1). FORMULA a(n) = ((n + 1)^4 - (1 + (-1)^n)/2)/2. G.f. 8*x*(1+x+x^2) / ( (1+x)*(1-x)^5 ). a(n) = 8*A011863(n). - R. J. Mathar, Jun 22 2011 a(n) = floor(n^4/2). [Wesley Ivan Hurt, Jun 14 2013] EXAMPLE a(1)=8 compositions of odd numbers into 4 parts <1 1:(0,0,0,1),(0,0,1,1),(0,1,0,0),(1,0,0,0) 3:(0,1,1,1),(1,0,1,1),(1,1,0,1),(1,1,1,0) MATHEMATICA Table[Floor[1/2*((n + 1)^4 - (1 + (-1)^n)/2)], {n, 0, 30}] PROG (MAGMA) [((n + 1)^4 - (1 + (-1)^n)/2)/2: n in [0..50]]; // Vincenzo Librandi, Jul 04 2011 CROSSREFS Cf. A171714. Sequence in context: A105374 A162668 A227733 * A028596 A264602 A125198 Adjacent sequences:  A191900 A191901 A191902 * A191904 A191905 A191906 KEYWORD nonn,easy AUTHOR Adi Dani, Jun 19 2011 STATUS approved

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Last modified June 24 01:22 EDT 2018. Contains 311819 sequences. (Running on oeis4.)