Number of compositions of 5*n-4 into parts 1 and 5.

Terms

a(0) =1a(1) =3a(2) =11a(3) =45a(4) =185a(5) =756a(6) =3084a(7) =12580a(8) =51320a(9) =209365a(10) =854126a(11) =3484490a(12) =14215310a(13) =57992715a(14) =236586825a(15) =965178576a(16) =3937538296a(17) =16063564001a(18) =65532845396a(19) =267347509271