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A322624
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a(n) = [x^n*y^n/(2*n)!] = (cosh(x)*cosh(y) + sinh(x) + sinh(y)) / (1 - sinh(x)*sinh(y)), for n >= 0.
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4
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1, 2, 30, 1040, 68390, 7322112, 1161583500, 256124504064, 74951279707590, 28111587450552320, 13150168194612783620, 7506080397628737060864, 5134940145279960796279772, 4147521174738722818202009600, 3905319571990498174351316679000, 4240383868623169668722969322455040, 5259293239338602314365337386168258630, 7389696615368349382565487880348756869120
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OFFSET
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0,2
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COMMENTS
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a(n) = binomial(2*n,n) * A322195(n) for n >= 0.
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LINKS
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PROG
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(PARI) {A322620(n, k) = my(X=x+x*O(x^n), Y=y+y*O(y^k));
C = cosh(X)*cosh(Y)/(1 - sinh(X)*sinh(Y));
S = (sinh(X) + sinh(Y))/(1 - sinh(X)*sinh(Y));
(n+k)!*polcoeff(polcoeff( C + S, n, x), k, y)}
for(n=0, 20, print1( A322620(n, n), ", "))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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