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 A182260 Number of ordered triples (w,x,y) with all terms in {1,...,n} and 2w
 0, 3, 11, 28, 56, 99, 159, 240, 344, 475, 635, 828, 1056, 1323, 1631, 1984, 2384, 2835, 3339, 3900, 4520, 5203, 5951, 6768, 7656, 8619, 9659, 10780, 11984, 13275, 14655, 16128, 17696, 19363, 21131, 23004, 24984, 27075, 29279, 31600, 34040 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Also the number of ordered triples (w,x,y) with all terms in {1,...,n} and 2w>x+y. A182260(n)+A055232(n)=3^(n-1). A182260 is row 1 of A211802 and also row 1 of A182259; see A211790 for a discussion and guide to related sequences. LINKS Index entries for linear recurrences with constant coefficients, signature (3,-2,-2,3,-1). FORMULA a(n) = 3*a(n-1)-2*a(n-2)-2*a(n-3)+3*a(n-4)-a(n-5). a(n) = (-1+(-1)^n-2*n^2+4*n^3)/8. G.f.: x^2*(3+2*x+x^2)/((1-x)^4*(1+x)). [Colin Barker, May 06 2012] EXAMPLE For n=2, the 3 triples (w,x,y) for which 2wx+y are (2,1,1), (2,1,2), (2,2,1). MATHEMATICA (See the program at A211802.) LinearRecurrence[{3, -2, -2, 3, -1}, {0, 3, 11, 28, 56}, 50] (* Harvey P. Dale, Aug 10 2019 *) CROSSREFS Cf. A211790, A211802. Sequence in context: A210611 A119074 A211810 * A163696 A092781 A332669 Adjacent sequences:  A182257 A182258 A182259 * A182261 A182262 A182263 KEYWORD nonn,easy AUTHOR Clark Kimberling, Apr 22 2012 STATUS approved

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Last modified June 4 06:41 EDT 2020. Contains 334822 sequences. (Running on oeis4.)