OFFSET
1,3
LINKS
MATHEMATICA
f[n_] := MultiplicativeOrder[5, n/(5^IntegerExponent[n, 5])]; Array[f, 80] (* Robert G. Wilson v, Jun 10 2011 *)
Table[Length[RealDigits[1/n, 5][[1, 1]]], {n, 90}]/.(0->1) (* Harvey P. Dale, Dec 28 2016 *)
PROG
(PARI) A007736(n, bas)={ local(p) ; for(sp=2, 1000000, for(s=1, sp-1, p=sp-s ; if( ((bas^p-1)*bas^s) % n == 0, return(p) ; ) ; ) ; ) ; return(-1) ; } { for(n=1, 100, print(n, " ", A007736(n, 5)) ; ) ; } \\ R. J. Mathar, Aug 30 2006
(PARI) a(n)=znorder(Mod(5, n/5^valuation(n, 5))) \\ Charles R Greathouse IV, Jun 10 2011
CROSSREFS
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Hal Sampson (hals(AT)easynet.com), David W. Wilson
STATUS
approved