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 A291107 Number of irredundant sets in the n-pan graph. 1
 3, 5, 7, 16, 26, 42, 72, 125, 216, 367, 629, 1079, 1852, 3173, 5438, 9323, 15984, 27401, 46971, 80522, 138039, 236639, 405665, 695425, 1192158, 2043700, 3503484, 6005970, 10295947, 17650192, 30257465, 51869927, 88919855, 152434004, 261315377, 447969116, 767946883 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Extended to a(1)-a(2) using the formula/recurrence. LINKS Eric Weisstein's World of Mathematics, Irredundant Set Eric Weisstein's World of Mathematics, Pan Graph Index entries for linear recurrences with constant coefficients, signature (1, 1, 0, 1, 0, -1). FORMULA a(n) = a(n-1) + a(n-2) + a(n-4) - a(n-6). G.f.: (x (3 + 2 x - x^2 + 4 x^3 - 5 x^5))/(1 - x - x^2 - x^4 + x^6). MATHEMATICA Table[RootSum[1 - #^2 - #^4 - #^5 + #^6 &, 59603 #^n - 12384 #^(1 + n) - 10700 #^(2 + n) + 17668 #^(3 + n) + 3457 #^(4 + n) + 1652 #^(5 + n) &]/89653, {n, 20}] LinearRecurrence[{1, 1, 0, 1, 0, -1}, {3, 5, 7, 16, 26, 42, 72, 125}, 20] CoefficientList[Series[(3 + 2 x - x^2 + 4 x^3 - 5 x^5)/(1 - x - x^2 - x^4 + x^6), {x, 0, 20}], x] CROSSREFS Sequence in context: A073436 A291736 A010070 * A132445 A307437 A070846 Adjacent sequences:  A291104 A291105 A291106 * A291108 A291109 A291110 KEYWORD nonn AUTHOR Eric W. Weisstein, Aug 17 2017 STATUS approved

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Last modified October 18 07:42 EDT 2019. Contains 328146 sequences. (Running on oeis4.)