This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A081648 #4 May 13 2018 09:50:06 %S A081648 82,85,90,97,106,117,130,145,162,163,166,171,178,187,198,211,226,243, %T A081648 244,247,252,259,268,279,292,307,325,328,333,340,349,360,373,388,405, %U A081648 406,409,414,421,430,454,469,486,487,490,495,502,511,522,535,550,567 %N A081648 Integers congruent to 0, 1, 4, 9, 16, 25, 36, 49 or 64 (mod 81) which are not squares. %D A081648 Mark A. Herkommer, Number Theory, A Programmer's Guide, McGraw-Hill, New York, 1999, page 315. %H A081648 Harvey P. Dale, <a href="/A081648/b081648.txt">Table of n, a(n) for n = 1..1000</a> %t A081648 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[ # ]] & ] %t A081648 Select[Range[600],IntegerQ[Sqrt[Mod[#,81]]]&&!IntegerQ[Sqrt[#]]&] (* _Harvey P. Dale_, May 13 2018 *) %Y A081648 Cf. A080151, A080160. %K A081648 easy,nonn %O A081648 1,1 %A A081648 _Robert G. Wilson v_, Mar 26 2003