OFFSET
0,3
LINKS
IBM Ponder This, Jan 01 2001
Index entries for linear recurrences with constant coefficients, signature (10,-27,18).
FORMULA
a(n) = 10*a(n-1)-27*a(n-2)+18*a(n-3) for n>3. - Colin Barker, Sep 13 2014
G.f.: -6*x^2*(3*x+2) / ((x-1)*(3*x-1)*(6*x-1)). - Colin Barker, Sep 13 2014
EXAMPLE
a(2)=12 since if aA indicates a zero length interval and a-A one of positive length the possibilities are: aA-b-B, b-aA-B, b-B-aA, bB-a-A, a-bB-A, a-A-bB, ab-A-B, ab-B-A, a-b-AB, b-a-AB, a-bA-B, b-a-AB.
PROG
(PARI) concat([0, 0], Vec(-6*x^2*(3*x+2)/((x-1)*(3*x-1)*(6*x-1)) + O(x^100))) \\ Colin Barker, Sep 13 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Henry Bottomley, Jan 19 2001
EXTENSIONS
More terms from Colin Barker, Sep 13 2014
STATUS
approved