OFFSET
0,13
COMMENTS
Number of compositions of n into parts p where 6 <= p <= 12. [Joerg Arndt, Jun 28 2013]
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,1,1,1,1,1,1,1).
FORMULA
a(n) = a(n-6) +a(n-7) +a(n-8) +a(n-9) +a(n-10) +a(n-11) +a(n-12) for n>11. - Vincenzo Librandi, Jun 28 2013
MATHEMATICA
CoefficientList[Series[1 / (1 - Total[x^Range[6, 12]]), {x, 0, 60}], x] (* Vincenzo Librandi, Jun 28 2013 *)
PROG
(Magma) m:=70; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^6-x^7-x^8-x^9-x^10-x^11-x^12))); /* or */ I:=[1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1]; [n le 12 select I[n] else Self(n-6)+Self(n-7)+Self(n-8)+Self(n-9)+Self(n-10)+Self(n-11)+Self(n-12): n in [1..70]]; // Vincenzo Librandi, Jun 28 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved