A124690 Position of the first n in the decimal expansion of Pi^n, or -1 if the digits of n never appear.

-1, 2, 47, 1, 3, 12, 2, 10, 3, 2, 159, 45, 348, 12, 129, 144, 31, 56, 196, 113, 57, 326, 19, 5, 33, 163, 75, 19, 69, 162, 8, 67, 176, 30, 88, 62, 64, 22, 49, 33, 170, 2, 97, 24, 183, 420, 119, 198, 241, 36, 114, 49, 6, 42, 17, 339, 92, 26, 16, 14, 68, 117, 350, 124, 8, 64, 69, 16, 20, 147, 76, 60, 17, 68, 188, 37, 105, 35, 356, 79

Offset

0,2

Comments

Conjecture: -1 only occurs in the first entry of the sequence. 2000 digits of precision was used in the calculation.

Links

Table of n, a(n) for n=0..79.

Formula

Pi = 3.1415926535...

Prog

(PARI) digitpospi(n) = \ Pi^n expansion first occurrence of n { local(x, y, r, dot); for(x=0, n, r = Pi^x; if(r==floor(r), y=find(Str(floor(r)), x), y=find(Str(r), x); dot=find(Str(r), "."); if(dot < y, y--); ); if(y, print1(y", "), print1(-1", ") ) ) } find(str, match) = \Return the position of the first occurrence of string \match in string str { local(lnm, lns, x, c, i); str=Str(str); \This allows leaving quotes off input match=Str(match); c=0; i=0; lns=length(str); lnm=length(match); if(lnm>1, i=1); x=1; while(x<=lns-lnm+1, if(mid(str, x, lnm)== match, break, x++); ); if(x>lns, return(0), return(x)) } mid(str, s, n) = \ Get a substring of length n from string str starting at position s in str. { local(v, ln, x, tmp); v =""; tmp = Vec(str); ln=length(tmp); for(x=s, s+n-1, v=concat(v, tmp[x]); ); return(v) } iscube(n) = { local(r); r = n^(1/3); if(floor(r+.5)^3== n, 1, 0) }

Crossrefs

Sequence in context: A000192 A196197 A273380 * A195877 A141579 A107205

Adjacent sequences: A124687 A124688 A124689 * A124691 A124692 A124693

Keyword

base,easy,sign

Author

Cino Hilliard, Dec 25 2006

Status

approved