OFFSET
0,2
COMMENTS
After a(10), the pattern seems to be sequences of sixteen a(n), four of which without solution, then 12 formed by placing a member of the binary sequence 1,10,11,11,100,101 etc. in front of re-occurring list of the same 12 4-digit numbers. The description does not lead to a unique sequence: a(0)=0 and a(0)=11 are both valid. a(3)=111 and a(3)=100 are both valid. - R. J. Mathar, Mar 14 2006
REFERENCES
John M, Yarbough, Digital Logic Applications and Design, West Publishing, 1997. p. 25
PROG
(PARI) dig(n, digno, base) = { local(nshif) ; nshif=n ; for(shifr=0, digno-1, nshif = floor(nshif/base) ) ; nshif % base ; } binrep(n) = { local(nshif, resul) ; nshif=n; resul = Str(dig(nshif, 0, 2)) ; nshif=floor(nshif/2) ; while (nshif != 0, resul = concat(Str(dig(nshif, 0, 2)), resul) ; nshif=floor(nshif/2) ; ) ; return(resul) ; } modN(n) = { local(resul) ; resul = 16*floor(n/16) ; resul += -1*dig(n, 0, 2) ; resul += 1*dig(n, 1, 2) ; resul += 3*dig(n, 2, 2) ; resul += 6*dig(n, 3, 2) ; return(resul) ; } { for (n = 0, 60, for(an =0, 1000, if( modN(an) == n, anS = binrep(an) ; print1(anS, ", ") ; break ; ) ; if( an==1000, print("-1, ") ); ) ; ) } - R. J. Mathar, Mar 14 2006
CROSSREFS
KEYWORD
easy,sign
AUTHOR
George E. Antoniou, Dec 15 2001
EXTENSIONS
More terms from R. J. Mathar, Mar 14 2006
STATUS
approved