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

Offset

1,1

Comments

a(20) > 10^14. - Giovanni Resta, Jul 27 2018

Links

Table of n, a(n) for n=1..19.

Eric Weisstein's World of Mathematics, Square Number

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 *)

Crossrefs

Cf. A036516, A034994.

Sequence in context: A323726 A087886 A123754 * A046181 A151993 A120053

Adjacent sequences: A048351 A048352 A048353 * A048355 A048356 A048357

Keyword

nonn,base,more

Author

Patrick De Geest, Mar 15 1999

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

Status

approved