A111491 - OEIS

A111491

a(0) = 1; for n>0, a(n) = (2^n-1)*a(n-1)-(-1)^n.

1, 2, 5, 36, 539, 16710, 1052729, 133696584, 34092628919, 17421333377610, 17822024045295029, 36481683220718924364, 149392492788843995270579, 1223673908433421165261312590, 20047449641864738950476084161969, 656894782414981901190249849735238224

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OFFSET

0,2

REFERENCES

W. T. Trotter, Combinatorics and Partially Ordered Sets, Johns Hopkins, 1992; see p. 195.

LINKS

Table of n, a(n) for n=0..15.

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

Cf. A111968.

Sequence in context: A275552 A086832 A317801 * A331402 A284605 A106129

Adjacent sequences: A111488 A111489 A111490 * A111492 A111493 A111494

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Nov 28 2005, typo corrected Nov 21 2008

STATUS

approved