A sequence related to the Somos-6 sequence A006722.

Terms

a(0) =1a(1) =1a(2) =-1a(3) =1a(4) =-3a(5) =-3a(6) =1a(7) =-25a(8) =49a(9) =1a(10) =385a(11) =1489a(12) =503a(13) =10753a(14) =-82371a(15) =-196419a(16) =-1575551a(17) =-12482641a(18) =95770849a(19) =-739310591a(20) =5684060161a(21) =45018762529a(22) =359479836623