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 A122447 Central terms of pendular trinomial triangle A122445. 7
 1, 0, 1, 2, 8, 28, 107, 418, 1676, 6848, 28418, 119444, 507440, 2175500, 9400207, 40895602, 178984212, 787503168, 3481278734, 15454765948, 68871993872, 307981243608, 1381569997998, 6215433403188, 28036071086296 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS G.f.: A(x) = 1/(1+x - x*B(x)) = (1 + x*H(x))/(1+x) = 1 + x^2*F(x)/B(x), where B(x) is g.f. of A122446, H(x) is g.f. of A122448, F(x) is g.f. of A122450. LINKS FORMULA G.f. satisfies: A(x) = 1+2*x - 2*x*(3+x)*A(x) + x*(4+3*x)*A(x)^2. G.f.: A(x) = ( 1+6x+2x^2 - sqrt(1-4x-4x^2+4x^4) )/( 2x(4+3x) ). PROG (PARI) {a(n)=polcoeff(2*(1+2*x)/(1+6*x+2*x^2+sqrt(1-4*x-4*x^2+4*x^4+x*O(x^n))), n)} CROSSREFS Cf. A122445, A122446, A122448, A122449, A122450, A122451, A122452. Sequence in context: A115967 A150714 A292668 * A150715 A026528 A150716 Adjacent sequences:  A122444 A122445 A122446 * A122448 A122449 A122450 KEYWORD nonn AUTHOR Paul D. Hanna, Sep 07 2006 STATUS approved

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Last modified December 15 22:02 EST 2019. Contains 330012 sequences. (Running on oeis4.)