A101552 C(n-3,3)+C(n-7,7)+...+C(n-(4*floor((n-4)/4)+3),4*floor((n-4)/4)+3).

0, 0, 0, 0, 0, 0, 1, 4, 10, 20, 35, 56, 84, 120, 166, 228, 322, 484, 785, 1352, 2396, 4248, 7405, 12592, 20856, 33728, 53524, 83912, 130956, 204968, 323665, 517356, 837206, 1368108, 2248479, 3700648, 6077900, 9938488, 16164330, 26154700, 42146078

Offset: 0

Author

Paul Barry, Dec 06 2004

Keywords

• easy
• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1,0,0,0,1).

Crossrefs

Cf. A024490, A101551.

Programs

Mathematica

CoefficientList[Series[x^6/((1 - x)^4 - x^8) , {x, 0, 50}], x] (* G. C. Greubel, May 17 2016 *)

Formula

G.f.: x^6/((1-x)^4-x^8).

a(n) = sum{k=0..n, if(mod(k+1, 4)=0, C(n-k, k), 0)}.

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + a(n-8). - G. C. Greubel, May 17 2016