A048350 a(n)^2 is the smallest square containing exactly n 5's.

5, 75, 235, 745, 22485, 22925, 235065, 505525, 2356384, 23569166, 227069495, 674919666, 3931354166, 7450205075, 39969432765, 524933839166, 2134374738666, 4904646324166, 23802428354166

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

k := 1; For[n = 1, n < 30000, n++, If[DigitCount[n^2][[5]] == k, k++; Print[n]]] (* Stefan Steinerberger, Apr 09 2006 *)
a[n_] := Module[{i = 1}, While[DigitCount[i^2][[6]] != n, i++; ]; i]; (* Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 20 2006 *)

Crossrefs

Cf. A036512, A034986, A048351.

Sequence in context: A355121 A156703 A285452 * A030991 A216093 A151752

Adjacent sequences: A048347 A048348 A048349 * A048351 A048352 A048353

Keyword

nonn,base,more

Author

Patrick De Geest, Mar 15 1999

Extensions

More terms from Jon E. Schoenfield, Jan 14 2009

One more term from Jon E. Schoenfield, Jan 25 2009

a(17)-a(19) from Giovanni Resta, Jul 27 2018

Status

approved