A124609 Position of the first 9 in the decimal expansion of the square root of n, or -1 if 9 never appears.

-1, -1, 15, 18, -1, 8, 4, 15, 15, -1, 16, 9, 24, 14, 14, 5, -1, 19, 13, 6, 8, 9, 3, 3, 3, -1, 3, 3, 3, 27, 22, 17, 10, 19, 5, 2, -1, 12, 11, 5, 20, 58, 9, 25, 7, 8, 7, 20, 2, -1, 33, 16, 11, 7, 7, 6, 24, 4, 14, 22, 5, 7, 19, 2, -1, 12, 14, 16, 18, 11, 19, 7, 18, 31, 22, 31, 6, 5, 29, 6, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -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: A113968 A093812 A159840 * A102500 A067757 A063779

Adjacent sequences: A124606 A124607 A124608 * A124610 A124611 A124612

Keyword

base,easy,sign

Author

Cino Hilliard, Dec 22 2006, corrected Jul 18 2007

Status

approved