OFFSET
1,3
LINKS
FORMULA
S(n; t, s) = S(n-1; t, s) + S(n-1; t+3, s+3t+1) + S(n-1; t+2, s+2t) + S(n-1; t+1, s+t+1).
Empirical g.f.: 4*x^3*(1-4*x+12*x^2-16*x^3+8*x^4) / ((1-4*x)*(1-4*x+8*x^2)*(1+16*x^4)). - Colin Barker, Feb 21 2016
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Frank Ruskey, Mar 29 2002
EXTENSIONS
Terms a(11) onward from Max Alekseyev, Apr 09 2013
STATUS
approved