A171672 Numbers n with property that n^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

1,2

Comments

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

Links

Table of n, a(n) for n=1..55.

Zak Seidov, Safe squares .

Zak Seidov, A171672: n^2 is safe number

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 *)

Crossrefs

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

Sequence in context: A182759 A022121 A364086 * A341262 A361992 A070073

Adjacent sequences: A171669 A171670 A171671 * A171673 A171674 A171675

Keyword

base,nonn

Author

Zak Seidov, Dec 15 2009

Extensions

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

Status

approved