A061104 Smallest number whose sum of digits is n^2.
0, 1, 4, 9, 79, 799, 9999, 499999, 19999999, 999999999, 199999999999, 49999999999999, 9999999999999999, 7999999999999999999, 7999999999999999999999, 9999999999999999999999999
Offset: 0
Examples
a(5) = 799, 7 + 9 + 9 = 25 = 5^2.
Links
- Harry J. Smith, Table of n, a(n) for n = 0..94
Programs
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PARI
a(n) = { (n^2%9 + 1)*10^(n^2\9) - 1 } \\ Harry J. Smith, Jul 18 2009
Formula
a(n) = A051885(n^2).
a(n) = ((n^2 mod 9) + 1)*10^floor(n^2/9) - 1. - Henry Bottomley, Apr 24 2001