Values of m for which a regular polygon with m sides cannot be constructed with ruler and compass.

Terms

a(0) =7a(1) =9a(2) =11a(3) =13a(4) =14a(5) =18a(6) =19a(7) =21a(8) =22a(9) =23a(10) =25a(11) =26a(12) =27a(13) =28a(14) =29a(15) =31a(16) =33a(17) =35a(18) =36a(19) =37a(20) =38a(21) =39a(22) =41a(23) =42a(24) =43a(25) =44a(26) =45a(27) =46a(28) =47a(29) =49