A096570 Number of compositions of n with first part 2 and no equal adjacent parts; this is column 2 of the array in A096568.

0, 1, 1, 0, 2, 4, 5, 10, 18, 29, 53, 95, 161, 283, 500, 869, 1524, 2673, 4665, 8170, 14313, 25032, 43817, 76710, 134228, 234938, 411242, 719720, 1259677, 2204816, 3858882, 6753956, 11821191, 20689807, 36212093, 63380145, 110930372, 194154783

Offset

1,5

Links

Table of n, a(n) for n=1..38.

Formula

Define s(0)=1, T(1, 1)=1 and T(i, j)=0 for j>i. For n>=2 and 1<=k<=n, define s(n)=T(n, 1)+T(n, 2)+...+T(n, n) and T(n, k)=s(n-k)-T(n-k, k). (This is array A096568.)

Crossrefs

Cf. A003242, A096568, A096569, A096571, A096572.

Sequence in context: A018401 A049332 A335206 * A046430 A133040 A018424

Adjacent sequences: A096567 A096568 A096569 * A096571 A096572 A096573

Keyword

nonn

Author

Clark Kimberling, Jun 27 2004

Status

approved