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 A322747 a(n) = sqrt(1 + A322746(2*n)). 3
 1, 5, 161, 8749, 665857, 65160501, 7793761249, 1101696200669, 179689877047297, 33215554576822501, 6862186181491284001, 1566923219786361397005, 391868347839681254572801, 106523078497331434142611733, 31273034455313887578671676257 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..296 Wikipedia, Chebyshev polynomials. FORMULA a(n) = Sum_{k=0..n} binomial(2*n, 2*k)*(2*n+1)^(n-k)*(2*n)^k. a(n) = A322790(2*n, n). a(n) = T_{n}(4*n+1) where T_{n}(x) is a Chebyshev polynomial of the first kind. a(n) ~ exp(1/4) * 2^(3*n - 1) * n^n. - Vaclav Kotesovec, Dec 25 2018 PROG (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)} CROSSREFS Cf. A322746, A322790. Sequence in context: A287032 A136368 A229163 * A274712 A117068 A185832 Adjacent sequences:  A322744 A322745 A322746 * A322748 A322749 A322750 KEYWORD nonn AUTHOR Seiichi Manyama, Dec 25 2018 STATUS approved

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Last modified May 29 09:00 EDT 2020. Contains 334697 sequences. (Running on oeis4.)