OFFSET
0,2
REFERENCES
W. T. Trotter, Combinatorics and Partially Ordered Sets, Johns Hopkins, 1992; see p. 195.
MAPLE
s:=proc(n) option remember; if n=0 then 1 else (2^n-1)*s(n-1)-(-1)^n; fi; end;
MATHEMATICA
RecurrenceTable[{a[0]==1, a[n]==(2^n-1)a[n-1]-(-1)^n}, a, {n, 20}] (* Harvey P. Dale, Dec 11 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 28 2005, typo corrected Nov 21 2008
STATUS
approved