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 A009530 Expansion of e.g.f. sin(tanh(x)/cos(x)). 2
 1, 0, 12, -336, -2096, -1043328, -29488704, -8894706432, -389860902656, -170568226222080, -6327905330549760, -6080018829202427904, 242897035394043301888, -323994054628796940582912, 123697309877515731773669376, -13142696592417683099946516480 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Among solutions to a(n)=2n are primes, twice primes (A001747) and also further numbers. LINKS MATHEMATICA Sin[ Tanh[ x ]/Cos[ x ] ] (* Odd Part *) PROG (PARI) x='x+O('x^34); v = Vec(serlaplace(sin(tanh(x)/cos(x)))); vector(#v\2, n, v[2*n-1]) \\ Michel Marcus, Apr 02 2017 CROSSREFS Sequence in context: A298245 A110101 A185247 * A159363 A009680 A218820 Adjacent sequences:  A009527 A009528 A009529 * A009531 A009532 A009533 KEYWORD sign AUTHOR EXTENSIONS Extended with signs by Olivier Gérard, Mar 15 1997 STATUS approved

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Last modified October 21 04:40 EDT 2019. Contains 328291 sequences. (Running on oeis4.)