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Search: id:A116467
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| 1, 2, 2, 4, 2, 4, 4, 8, 18, 52, 164, 544, 1852, 6416, 22520, 79888, 285938, 1031316, 3744628, 13676384, 50209860, 185190400, 685888736, 2549873880, 9511787452, 35592025904, 133559834064, 502494233128, 1895089009088, 7162963968712
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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G.f.: A(x) = 2*(1-6*x+2*x^2+6*x^3+3*x^4)/(2-10*x-x^2)/(1-x)^2 + x*(2+x)*(1-4*x)/(2-10*x-x^2)/2*deriv(A(x)).
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PROGRAM
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(PARI) {a(n)=sum(k=0, n, polcoeff(polcoeff(1/(1-x*y)+ x*(1+x-2*x^2*y)/(1-x)/(1+x+x*y+x*O(x^n)+y*O(y^k))/(1-x*y), n, x), k, y)^2)}
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CROSSREFS
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Cf. A114700 (triangle), A116466 (unsigned row sums).
Sequence in context: A001316 A096865 A116466 this_sequence A079314 A060609 A109526
Adjacent sequences: A116464 A116465 A116466 this_sequence A116468 A116469 A116470
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Feb 19 2006
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