Number of fixed polyhexes of area n with holes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =1a(6) =12a(7) =99a(8) =696a(9) =4476a(10) =27249a(11) =159940a(12) =915113a(13) =5139576a(14) =28466304a(15) =155985402a(16) =847589346a(17) =4574772507a(18) =24557645009a(19) =131237632524a(20) =698734393764