A171672 Numbers m with property that m^2 is not of form (k + sum of digits of k).

1, 3, 8, 11, 20, 76, 83, 86, 94, 97, 104, 110, 133, 137, 166, 173, 176, 184, 187, 194, 223, 256, 263, 264, 266, 274, 275, 277, 284, 332, 353, 356, 364, 367, 396, 403, 407, 436, 443, 454, 457, 464, 504, 533, 535, 546, 587, 623, 624, 625, 634, 637, 644, 654, 673

Offset: 1

Author

Zak Seidov, Dec 15 2009

Keywords

• base
• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Zak Seidov, Self squares.
• Zak Seidov, A171672: n^2 is safe number.

Crossrefs

Cf. A003052 (self or Colombian numbers), A171671 (m^2 are self numbers), A062028 (a(n) = n + sum of the digits of n), A171673 (n and n^2 are self numbers).

Programs

Mathematica

nn=5*10^5; list=Table[n + Total[IntegerDigits[n]],{n,nn}]; Select[Sqrt[Complement[Range[nn],list]], IntegerQ[#] &] (* Jayanta Basu, May 06 2013 *)

Formula

a(n) = sqrt(A171671(n)).

Extensions

Changed the word "safe" in this entry to "self". - N. J. A. Sloane, Feb 26 2017