a(n) is number of strings of length n that can be obtained by starting with abc and repeatedly doubling any substring in place and then discarding any string that contains two successive equal letters.
A135017
a(n) is number of strings of length n that can be obtained by starting with abc and repeatedly doubling any substring in place and then discarding any string that contains two successive equal letters.
Terms
- a(0) =0a(1) =0a(2) =1a(3) =0a(4) =2a(5) =1a(6) =3a(7) =5a(8) =7a(9) =15a(10) =20a(11) =48a(12) =60a(13) =156a(14) =205a(15) =489a(16) =761a(17) =1572a(18) =2796a(19) =5357a(20) =10174a(21) =19021a(22) =37272a(23) =69375a(24) =137759a(25) =258444a(26) =513696a(27) =976890a(28) =1934900a(29) =3727164
External references
- oeis: A135017