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 A191678 Number of lattice paths from (0,0) to (n,n) using steps (1,0), (1,1), (0,2), (2,2). 0
 1, 1, 5, 15, 62, 233, 937, 3729, 15121, 61492, 251942, 1036215, 4279754, 17731181, 73670725, 306823695, 1280574706, 5354602495, 22426876445, 94070238840, 395106054632, 1661489413472, 6994494531010, 29474635716345, 124319047552309, 524797934104312, 2217091297558466, 9373180869094923 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA G.f.: A(x) where (4*x^6+12*x^5-20*x^3+27*x^2+12*x-4)*A(x)^3-(3*x^2+3*x-3)*A(x)+1 = 0. - Mark van Hoeij, Apr 17 2013 MAPLE P := (4*x^6+12*x^5-20*x^3+27*x^2+12*x-4)*A^3-(3*x^2+3*x-3)*A+1; Q := eval(P, A=A+1): series(RootOf(Q, A)+1, x=0, 30);  # Mark van Hoeij, Apr 17 2013 PROG (PARI) /* same as in A092566 but use */ steps=[[1, 0], [1, 1], [0, 2], [2, 2]]; /* Joerg Arndt, Jun 30 2011 */ CROSSREFS Cf. A001850, A026641, A036355, A137644, A192364, A192365, A192369, A191354. Sequence in context: A149605 A149606 A019045 * A149607 A149608 A149609 Adjacent sequences:  A191675 A191676 A191677 * A191679 A191680 A191681 KEYWORD nonn AUTHOR Joerg Arndt, Jun 30 2011 STATUS approved

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Last modified October 19 04:40 EDT 2019. Contains 328211 sequences. (Running on oeis4.)