A334161 Least positive integer whose square root starts with just n odd decimal digits.

4, 1, 10, 3, 63, 129, 91, 1123, 249, 384, 3131, 391, 2823, 14293, 9996, 100603, 17260, 140863, 999960, 39984, 1837521, 11289570, 999996, 26336742, 3999840, 15999968, 29116075, 26824089, 366858085, 308642, 99999996, 314558578, 6399999872, 1599999968, 381808465

Offset

0,1

Comments

We also have a(49) = 39999999984, a(54) = 3999999999840, a(59) = 3999999999984. - Giovanni Resta, Apr 18 2020

Links

Giovanni Resta, Table of n, a(n) for n = 0..46

Example

Square root of first terms: 2, 1.0, 3.16, 1.732, 7.9372, 11.3578, ...

Prog

(PARI) a(n) = {my(g=10^n, v); for(k=1, oo, v=digits(floor(sqrtint(k*g^2)))[1..n+1]; if(v[n+1]%2==0 && setintersect([1, 3, 5, 7, 9], v=Set(v[1..n]))==v, return(k))); }

Crossrefs

Cf. A210492, A333827.

Sequence in context: A108759 A158824 A348074 * A039806 A030320 A379818

Adjacent sequences: A334158 A334159 A334160 * A334162 A334163 A334164

Keyword

nonn,base

Author

Jinyuan Wang, Apr 16 2020

Extensions

Terms a(30) and beyond from Giovanni Resta, Apr 18 2020

Status

approved