a(n) is the binary XOR of all n-bit triangular numbers.

Terms

a(0) =1a(1) =3a(2) =6a(3) =5a(4) =9a(5) =62a(6) =70a(7) =204a(8) =348a(9) =586a(10) =1770a(11) =3582a(12) =6974a(13) =9046a(14) =22486a(15) =12225a(16) =54977a(17) =97140a(18) =201076a(19) =34728a(20) =347048a(21) =1031920a(22) =2250480a(23) =10857648a(24) =24157360a(25) =40826080a(26) =112612576a(27) =21772545a(28) =130349313a(29) =1060428174