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 A155121 2*n*(1+n+n^2+n^3)-3. 2
 -3, 5, 57, 237, 677, 1557, 3105, 5597, 9357, 14757, 22217, 32205, 45237, 61877, 82737, 108477, 139805, 177477, 222297, 275117, 336837, 408405, 490817, 585117, 692397, 813797, 950505, 1103757, 1274837, 1465077, 1675857 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..2000 Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1). FORMULA a(n) = 2*n*(1+n+n^2+n^3)-3. G.f.: (3-20*x-2*x^2-32*x^3+3*x^4)/(x-1)^5. a(n) = 4*A071237(n)-3. a(n) = 2*A024003(n)/(1-n)-5 (n>1). - Bruno Berselli, Dec 16 2010 MATHEMATICA Table[ -3 + 2 n + 2 n^2 + 2 n^3 + 2 n^4, {n, 0, 30}] PROG (MAGMA) [2*n*(1+n+n^2+n^3)-3: n in [0..40] ]; // Vincenzo Librandi, May 23 2011 CROSSREFS Cf. A155120, A142463. Sequence in context: A087602 A086340 A248923 * A106914 A049190 A174920 Adjacent sequences:  A155118 A155119 A155120 * A155122 A155123 A155124 KEYWORD sign,easy AUTHOR Roger L. Bagula, Jan 20 2009 STATUS approved

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