Number of 2n-bead necklaces labeled with numbers 1..5 allowing reversal, with neighbors differing by exactly 1.

A208668

Number of 2n-bead necklaces labeled with numbers 1..5 allowing reversal, with neighbors differing by exactly 1.

Terms

    a(0) =4a(1) =7a(2) =12a(3) =23a(4) =44a(5) =97a(6) =212a(7) =512a(8) =1260a(9) =3251a(10) =8540a(11) =23035a(12) =62780a(13) =173453a(14) =482692a(15) =1353077a(16) =3811364a(17) =10785235a(18) =30625196a(19) =87239999a(20) =249174236a(21) =713416601a(22) =2046945140a(23) =5884580074a(24) =16946835092a(25) =48883925867a(26) =141217957620a(27) =408519816611

External references