Sequence arising in search for Legendre sequences.

Terms

a(0) =1a(1) =2a(2) =2a(3) =9a(4) =17a(5) =18a(6) =82a(7) =146a(8) =209a(9) =408a(10) =1113a(11) =1540a(12) =3294a(13) =7076a(14) =11308a(15) =10940a(16) =39014a(17) =46470a(18) =109780