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%I #5 Sep 30 2025 20:34:16
%S 1,3,5,-217,2505,765963,-6838195,-9335128657,286658869905,
%T 407628336475923,-19130907180121195,-42164783730598660297,
%U 3124552441785986300505,9154657902519091515622683
%N arcsinh(sec(x)*sinh(x))=x+3/3!*x^3+5/5!*x^5-217/7!*x^7+2505/9!*x^9...
%K sign
%O 0,2
%A _Patrick Demichel_