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 A356547 Triangle read by rows. T(n, k) are the coefficients of polynomials p_n(x) based on the Eulerian numbers of second order representing the Bernoulli numbers as B_n = p_n(1) / (2*(2*n - 1)!). 3
 1, 1, 0, 6, -4, 0, 120, -192, 72, 0, 5040, -15840, 13920, -3456, 0, 362880, -2096640, 3306240, -1918080, 345600, 0, 39916800, -413683200, 1053803520, -1064448000, 448519680, -62208000, 0, 6227020800, -114960384000, 447866496000, -699342336000, 506348236800, -164428185600, 18289152000, 0 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS The Bernoulli numbers with B(1) = 1/2 can be represented as the weighted sum of Eulerian numbers of second order, where we use the definition as given by Graham et al., Eulerian2(n, k) = A201637(n, k). For n >= 1 we have B_(n) = (1/2)*Sum_{k=0..n} (-1)^k*Eulerian2(n, k) / binomial(2*n - 1, k). Although this representation looks classical it was apparently first proved by Majer in 2010; later Fu and recently O'Sullivan gave an alternative proof (see links). An analogous representation based on the Eulerian numbers of first order is given in A356545. REFERENCES R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics, 2nd ed. Addison-Wesley, Reading, MA, 1994, p. 270. (Since the thirty-fourth printing, Jan. 2022, with B(1) = 1/2.) LINKS Table of n, a(n) for n=0..35. Amy M. Fu, Some Identities Related to the Second-Order Eulerian Numbers, arXiv:2104.09316 [math.CO], Apr. 2021. Peter Luschny, How are the Eulerian numbers of the first-order related to the Eulerian numbers of the second-order?, MathOverflow, Feb. 2021. Pietro Majer, Expressions involving Eulerian numbers of the second kind, MathOverflow, Nov 2010. G. Rzadkowski, M. Urlinska, A Generalization of the Eulerian Numbers, arXiv:1612.06635 [math.CO], 2016 Cormac O'Sullivan, Stirling's approximation and a hidden link between two of Ramanujan's approximations, arXiv:2208.02898 [math.NT], Aug. 2022. FORMULA Let p_n(x) = Sum_{k=0..n} Eulerian2(n, k)*k!*(2*n - k - 1)! * (-x)^k. T(n, k) = [x^k] p_n(x). T(n, k) = (-1)^k*Eulerian2(n, k)*k!*(2*n - k - 1)!. EXAMPLE The triangle T(n, k) of the coefficients, sorted in ascending order, starts: [0] 1; [1] 1, 0; [2] 6, -4, 0; [3] 120, -192, 72, 0; [4] 5040, -15840, 13920, -3456, 0; [5] 362880, -2096640, 3306240, -1918080, 345600, 0; [6] 39916800, -413683200, 1053803520, -1064448000, 448519680, -62208000, 0; MAPLE E2 := proc(n, k) combinat:-eulerian2(n, k) end: p := (n, x) -> `if`(n = 0, 1, add(E2(n, k)*k!*(2*n - k - 1)!*(-x)^k, k = 0..n)): seq(print([n], seq(coeff(p(n, x), x, k), k = 0..n)), n = 0..7); seq(`if`(n = 0, 1, p(n, 1)/(2*(2*n-1)!)), n = 0..14); # check Bernoulli numbers CROSSREFS Cf. A201637 (Eulerian number 2nd order), A164555(n)/A027642(n) (Bernoulli numbers with B(1) = 1/2). Cf. A356545. Sequence in context: A197581 A323525 A166978 * A365956 A365953 A365955 Adjacent sequences: A356544 A356545 A356546 * A356548 A356549 A356550 KEYWORD sign,tabl AUTHOR Peter Luschny, Aug 12 2022 STATUS approved

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Last modified August 3 12:10 EDT 2024. Contains 374893 sequences. (Running on oeis4.)