OFFSET
0,8
COMMENTS
a(n-1) is the number of compositions of n with at least one part >=7. - Joerg Arndt, Aug 06 2012
LINKS
Index entries for linear recurrences with constant coefficients, signature (3,-1,-1,-1,-1,-1,-2).
FORMULA
G.f.: x^6/ ( (2*x-1)*(x^6+x^5+x^4+x^3+x^2+x-1) ). - Joerg Arndt, Aug 06 2012
a(n) = 2^n - A001592(n+6). - R. J. Mathar, Aug 06 2012
MATHEMATICA
LinearRecurrence[{3, -1, -1, -1, -1, -1, -2}, {0, 0, 0, 0, 0, 0, 1}, 40] (* Harvey P. Dale, Dec 06 2018 *)
PROG
(PARI)
N=66; x='x+O('x^N);
gf = (1-x)/(1-2*x); /* A011782(n): compositions of n */
gf -= 1/(1 - (x+x^2+x^3+x^4+x^5+x^6)); /* A001592(n+5): compositions of n into parts <=6 */
v143662=Vec(gf + 'a0); v143662[1]=0; /* kludge to get all terms */
v143662 /* show terms */
/* Joerg Arndt, Aug 06 2012 */
CROSSREFS
KEYWORD
nonn
AUTHOR
DoZerg (daidodo(AT)gmail.com), Aug 28 2008
STATUS
approved