A048354 a(n)^2 is the smallest square containing exactly n 9's.
3, 63, 173, 1414, 17313, 53937, 138923, 953937, 3082207, 31622764, 99849687, 301579177, 3033150173, 14142134563, 141413973847, 543315746063, 3098361825223, 5477225574409, 14139412282687, 314896807700437, 412286308285783, 3147904051904219, 9055381813816577, 311447546136054827, 282841298257395573
Offset: 1
Links
- Eric Weisstein's World of Mathematics, Square Number
Programs
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Mathematica
a[n_]:=Module[{i},i=1;While[DigitCount[i^2][[9]]!=n,i++ ];i]; (* Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 23 2006 *)
Extensions
a(13)-a(15) from Jon E. Schoenfield, Jan 24 2009
a(16) from Jon E. Schoenfield, Jan 25 2009
a(17)-a(19) from Giovanni Resta, Jul 27 2018
a(20)-a(25) from Max Alekseyev, Mar 06 2025