A171673 Numbers n with property that both n and n^2 are self numbers (A003052).

1, 3, 20, 86, 97, 110, 176, 187, 266, 277, 356, 367, 457, 637, 714, 716, 727, 804, 815, 894, 984, 1087, 1177, 1267, 1357, 1436, 1537, 1614, 1616, 1627, 1704, 1715, 1884, 1985, 2077, 2235, 2257, 2516, 2694, 2784, 2885, 3045, 3135, 3315, 3326, 3337, 3414

Offset: 1

Author

Zak Seidov, Dec 15 2009

Keywords

• base
• nonn

Links

• David A. Corneth, Table of n, a(n) for n = 1..10000
• Zak Seidov, A171673

Crossrefs

Cf. A003052 (Self or Colombian numbers), A171671 (self squares), A171672 (n^2 are self squares).

Programs

Mathematica

nn=1.2*10^7; list=Table[n + Total[IntegerDigits[n]],{n,nn}]; se=Complement[Range[nn],list]; se1=Select[Sqrt[se],IntegerQ[#]&]; Intersection[se,se1] (* Jayanta Basu, May 06 2013 *)

Extensions

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