OFFSET
1,1
LINKS
Paul K. Stockmeyer, Variations on the Four-Post Tower of Hanoi Puzzle, Congressus Numerantium 102 (1994), pp. 3-12;
Paul Zimmermann, Sage program
FORMULA
Conjecture: for n >= 9, a(n) = a(n-1)+2*a(n-3)+c(n), where c(n) = 18 for odd n and c(n) = 14 for even n. - Paul Zimmermann, Oct 23 2017
Conjectures from Colin Barker, Oct 25 2017: (Start)
G.f.: 2*x*(1 + 3*x + 4*x^2 + 4*x^3 + 2*x^4 + 2*x^5 + 2*x^6 - 2*x^9) / ((1 - x)*(1 + x)*(1 - x - 2*x^3)).
a(n) = a(n-1) + a(n-2) + a(n-3) -2*a(n-5) for n>10. [corrected by Paul Zimmermann, Oct 07 2020
(End)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Sep 27 2017, following a suggestion from Paul Zimmermann who computed the terms through a(16).
EXTENSIONS
Extended through a(21) by Paul Zimmermann, Oct 23 2017
Name clarified by Paul Zimmermann, Oct 29 2017
STATUS
approved