login
A116973
If n mod 2 = 0 then (3^(n+3)-19)/8 else (3^(n+3)-1)/8.
1
1, 10, 28, 91, 271, 820, 2458, 7381, 22141, 66430, 199288, 597871, 1793611, 5380840, 16142518, 48427561, 145282681, 435848050, 1307544148, 3922632451, 11767897351, 35303692060, 105911076178, 317733228541, 953199685621
OFFSET
0,2
COMMENTS
Number of moves to solve Type 4 Zig-Zag puzzle.
REFERENCES
Richard I. Hess, Compendium of Over 7000 Wire Puzzles, privately printed, 1991.
Richard I. Hess, Analysis of Ring Puzzles, booklet distributed at 13th International Puzzle Party, Amsterdam, Aug 20 1993.
LINKS
FORMULA
a(n) = 2*a(n-1)+3*a(n-2)+5, a(0)=1; a(1)=1. - Zerinvary Lajos, Dec 14 2008
a(n) = (3^(n+3) - 19^((n+1) mod 2))/8. - Wesley Ivan Hurt, Nov 13 2013
MAPLE
f:=n->if n mod 2 = 0 then (3^(n+3)-19)/8 else (3^(n+3)-1)/8; fi;
a[0]:=1:a[1]:=1:for n from 2 to 50 do a[n]:=2*a[n-1]+3*a[n-2]+5 od: seq(a[n], n=1..33); # Zerinvary Lajos, Dec 14 2008
MATHEMATICA
f[n_]:=Module[{c=3^(n+3)}, If[EvenQ[n], (c-19)/8, (c-1)/8]]; Array[f, 30, 0] (* Harvey P. Dale, Oct 23 2012 *)
CROSSREFS
Sequence in context: A251319 A126364 A076712 * A352180 A350990 A264579
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Apr 01 2006
STATUS
approved