From a nim-like game.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =8a(6) =11a(7) =14a(8) =18a(9) =24a(10) =32a(11) =43a(12) =54a(13) =68a(14) =86a(15) =110a(16) =142a(17) =185a(18) =239a(19) =307a(20) =393a(21) =503a(22) =645a(23) =830a(24) =1069a(25) =1376a(26) =1769a(27) =2272a(28) =2917a(29) =3747