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A124605
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Position of the first 5 in the decimal expansion of the square root of n, or -1 if 5 never appears.
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0
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-1, -1, 8, 6, -1, 37, 31, 4, 36, -1, 26, 12, 10, 4, 6, 19, -1, 7, 16, 3, 7, 2, 7, 4, 10, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, 8, 18, 19, 5, 38, 22, 2, 8, 23, 13, 3, 13, -1, 13, 11, 8, 14, 14, 13, 11, 2, 4, 7, 4, 10, 22, 6, -1, 6, 13, 4, 9, 18, 10, 15, 4, 2, 7, 6, 45, 35, 18, 13, 15, -1, 3, 8, 4, 5, 10, 9, 8, 12, 11, 2, 2, 6, 4, 39, 6, 6, 16, 17, -1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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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); }
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CROSSREFS
| Sequence in context: A153493 A113212 A070483 * A021120 A021541 A066716
Adjacent sequences: A124602 A124603 A124604 * A124606 A124607 A124608
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KEYWORD
| base,easy,sign
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AUTHOR
| Cino Hilliard (hillcino368(AT)hotmail.com), Dec 22 2006, corrected Jul 18 2007
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