A124606 Position of the first 6 in the decimal expansion of the square root of n, or -1 if 6 never appears.

-1, -1, 9, 12, -1, 4, 39, 2, 13, -1, 3, 4, 3, 2, 5, 10, -1, 8, 5, 14, 30, 8, 2, 27, 12, -1, 39, 4, 8, 6, 14, 3, 2, 6, 37, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, 6, 30, 19, 41, 6, 4, 21, 17, 2, 2, 6, 8, 20, 27, -1, 3, 11, 18, 4, 4, 3, 4, 48, 18, 2, 2, 24, 6, 6, 26, 20, -1, 16, 23, 3, 30, 5, 34, 11, 13, 4, 12, 5, 2, 2, 4, 25, 13, 10, 12, -1

Offset

0,3

Links

Table of n, a(n) for n=0..100.

Prog

(PARI) digitpos(n, m) = /* m-th digit in sqrt expansions */ { local(x, y, r, dot); default(realprecision, 1000); for(x=0, n, r = sqrt(x); if(issquare(x), y=find(Str(floor(r)), m), y=find(Str(r), m); dot=find(Str(r), "."); if(dot < y, y--); ); if(y, print1(y", "), print1(-1", ") ) ) } find(str, match) = /* Revised 2007 */ { local(lnm, lns, tstr, vstr, x, j); vstr=Vec(Str(str)); match=Str(match); lns=length(str); lnm=length(match); for(x=1, lns-lnm+1, tstr=""; for(j=x, x+lnm-1, tstr=concat(tstr, vstr[j]); ); if(match==tstr, return(x)) ); return(0); }

Crossrefs

Sequence in context: A352004 A196509 A269026 * A110647 A347943 A335168

Adjacent sequences: A124603 A124604 A124605 * A124607 A124608 A124609

Keyword

base,easy,sign

Author

Cino Hilliard, Dec 22 2006, corrected Jul 18 2007

Status

approved