OFFSET
4,2
LINKS
Georg Fischer, Table of n, a(n) for n = 4..200
Index entries for linear recurrences with constant coefficients, signature (3,-2,-1,0,1,2,-3,1).
FORMULA
G.f.: x^4*(x^3+x^2+1)/((1-x^2)*(1-x^3)*(1-x)^3) (conjectured). - Ralf Stephan, Mar 07 2004
a(n) = A055364(4 - n) for all n in Z. - Michael Somos, Jun 29 2015
EXAMPLE
G.f. = x^4 + 3*x^5 + 8*x^6 + 18*x^7 + 35*x^8 + 62*x^9 + 103*x^10 + ...
MATHEMATICA
a[ n_] := Quotient[ 3 n^4 - 20 n^3 + 54 n^2 - 60 n + 32, 144];
PROG
(PARI) {a(n) = (3*n^4 - 20*n^3 + 54*n^2 - 60*n + 32) \ 144}; /* Michael Somos, Jun 29 2015 */
(PARI) {a(n) = if( n<0, n = -1-n; polcoeff( (1 + x + x^3) / ((1 - x)^3 * (1 - x^2) * (1 - x^3)) + x * O(x^n), n), polcoeff( x^4 * (1 + x^2 + x^3) / ((1 - x)^3 * (1 - x^2) * (1 - x^3)) + x * O(x^n), n))}; /* Michael Somos, Jun 29 2015 */
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Christian G. Bower, May 09 2000
STATUS
approved