|
|
A068788
|
|
S(n; 1,3) = S(n; 3,3) where S(n; t,s) is the number of length n 4-ary strings whose digits sum to t mod 4 and whose sum of products of all pairs of digits sum to s mod 4.
|
|
10
|
|
|
0, 0, 4, 16, 80, 320, 1120, 4096, 15360, 61440, 254464, 1048576, 4259840, 17039360, 67624960, 268435456, 1069547520, 4278190080, 17146445824, 68719476736, 275146342400, 1100585369600, 4400191897600, 17592186044416, 70351564308480, 281406257233920
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
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
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|