The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A068789 S(n; 2,0) 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. 9
1, 2, 4, 16, 56, 272, 1184, 4608, 17536, 65792, 254464, 1017856, 4130816, 16781312, 67641344, 270532608, 1077968896, 4295032832, 17146445824, 68585783296, 274609995776, 1099512676352, 4400196091904, 17600775979008, 70385932435456, 281474993487872 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
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.: x*(1-8*x+24*x^2-24*x^3-24*x^4+32*x^5+64*x^6-192*x^7) / ((1-2*x)*(1-4*x)*(1-4*x+8*x^2)*(1+16*x^4)). - Colin Barker, Feb 21 2016
CROSSREFS
Sequence in context: A053503 A308381 A153957 * A009624 A009161 A009290
KEYWORD
nonn,base
AUTHOR
Frank Ruskey, Mar 29 2002
EXTENSIONS
Terms a(11) onward from Max Alekseyev, Apr 09 2013
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 17 21:09 EDT 2024. Contains 373464 sequences. (Running on oeis4.)