A081648 Integers congruent to 0, 1, 4, 9, 16, 25, 36, 49 or 64 (mod 81) which are not squares.

82, 85, 90, 97, 106, 117, 130, 145, 162, 163, 166, 171, 178, 187, 198, 211, 226, 243, 244, 247, 252, 259, 268, 279, 292, 307, 325, 328, 333, 340, 349, 360, 373, 388, 405, 406, 409, 414, 421, 430, 454, 469, 486, 487, 490, 495, 502, 511, 522, 535, 550, 567

Offset: 1

Author

Robert G. Wilson v, Mar 26 2003

Keywords

• easy
• nonn

References

• Mark A. Herkommer, Number Theory, A Programmer's Guide, McGraw-Hill, New York, 1999, page 315.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A080151, A080160.

Programs

Mathematica

Select[ Range[567], (Mod[ #, 81] == 0 || Mod[ #, 81] == 1 || Mod[ #, 81] == 4 || Mod[ #, 81] == 9 || Mod[ #, 81] == 16 || Mod[ #, 81] == 25 || Mod[ #, 81] == 36 || Mod[ #, 81] == 49 || Mod[ #, 81] == 64) && !IntegerQ[ Sqrt[ # ]] & ]
Select[Range[600],IntegerQ[Sqrt[Mod[#,81]]]&&!IntegerQ[Sqrt[#]]&] (* Harvey P. Dale, May 13 2018 *)