Nonprime numbers k of the form 4*m+1 such that Sum_{j=0..k-1} 2^j * binomial(3*j, j) == 1 (mod k).

Terms

a(0) =1a(1) =9a(2) =21a(3) =185a(4) =297a(5) =341a(6) =405a(7) =861a(8) =1113a(9) =1645a(10) =1677a(11) =1833a(12) =2409a(13) =3417a(14) =3621a(15) =4545a(16) =6141a(17) =8549a(18) =8949a(19) =8961a(20) =9309a(21) =10205a(22) =11049a(23) =12441a(24) =15621a(25) =16617a(26) =17313a(27) =18093a(28) =18357a(29) =19401