Coefficients of 1/(Sum_{k>=0} [(k+1)*r]*(-x)^k), where r = Pi/2 and [ ] = floor.

Terms

a(0) =1a(1) =3a(2) =5a(3) =9a(4) =18a(5) =36a(6) =72a(7) =144a(8) =287a(9) =570a(10) =1132a(11) =2250a(12) =4473a(13) =8892a(14) =17676a(15) =35137a(16) =69847a(17) =138845a(18) =276002a(19) =548649a(20) =1090629a(21) =2168001a(22) =4309649a(23) =8566912a(24) =17029689a(25) =33852374a(26) =67293256a(27) =133768530a(28) =265911039a(29) =528589801