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A322747
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a(n) = sqrt(1 + A322746(2*n)).
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3
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1, 5, 161, 8749, 665857, 65160501, 7793761249, 1101696200669, 179689877047297, 33215554576822501, 6862186181491284001, 1566923219786361397005, 391868347839681254572801, 106523078497331434142611733, 31273034455313887578671676257
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = Sum_{k=0..n} binomial(2*n, 2*k)*(2*n+1)^(n-k)*(2*n)^k.
a(n) = T_{n}(4*n+1) where T_{n}(x) is a Chebyshev polynomial of the first kind.
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PROG
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(PARI) {a(n) = sum(k=0, n, binomial(2*n, 2*k)*(2*n+1)^(n-k)*(2*n)^k)}
(PARI) {a(n) = polchebyshev(n, 1, 4*n+1)}
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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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