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 A326328 a(n) = (2*n)! [x^(2*n)] cosh(x)^(-3). 1
 1, -3, 33, -723, 25953, -1376643, 101031873, -9795436563, 1212135593793, -186388033956483, 34859622790687713, -7791941518975112403, 2051293521728340489633, -628173356956461494680323, 221398076445213367209575553, -88980467736394156270609236243, 40450409313733718675802456121473 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Apparently all terms except the initial 1 have 3-valuation 1. - F. Chapoton, Nov 25 2021 LINKS Table of n, a(n) for n=0..16. MAPLE egf := cosh(z)^(-3): ser := series(egf, z, 36): seq((2*n)!*coeff(ser, z, 2*n), n=0..16); CROSSREFS Row 3 of A326327. Sequence in context: A364242 A091462 A340971 * A233319 A003715 A247030 Adjacent sequences: A326325 A326326 A326327 * A326329 A326330 A326331 KEYWORD sign AUTHOR Peter Luschny, Jul 07 2019 STATUS approved

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Last modified August 8 14:00 EDT 2024. Contains 375021 sequences. (Running on oeis4.)