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 A243985 #18 Aug 21 2014 20:42:44 %S A243985 1,3,4,8,9,16,20,22,24,27,35,48,64,90,94,115,119,143,170,171,192,200, %T A243985 214,216,217,265,310,322,323,343,382,497,517,527,656,679,710,729,742, %U A243985 745,782,862,889,899,935,970,1066,1174,1177,1207,1219,1270,1393,1426 %N A243985 Numbers n such that A243984(n), the sum of non-twin divisors of n, is a square. %C A243985 See A243917 for definition of non-twin divisor. %C A243985 Squares included in the sequence are : 1, 4, 9, 16, 64, 729, ... %H A243985 Michael De Vlieger, <a href="/A243985/b243985.txt">Table of n, a(n) for n = 1..8692</a> (a(n) < 5,000,000) %e A243985 The positive divisors of 8 are 1, 2, 4, 8. Of these, 1 and 8 are non-twin divisors. So 8 is in this sequence, which is 1 + 8 = 3^2. %t A243985 a243984[n_Integer] := Total[Select[Divisors[n], If[And[# <= 2 || Divisible[n, # - 2] == False, Divisible[n, # + 2] == False], True, False] &]]; a243985[n_Integer] := Flatten@Select[Position[Sqrt[a243984 /@ Range[n]], _?IntegerQ], If[Length[#] == 1, True, False] &]; a243985[1500] (* _Michael De Vlieger_, Aug 17 2014 *) %o A243985 (PARI) %o A243985 A243984(n) = s=0; fordiv(n, d, if(!((d>2 && n%(d-2)==0) || (d<=n-2 && n%(d+2)==0)), s+=d)); s %o A243985 for(n=1, 200, if(issquare(A243984(n)), print1(n, ", "))) \\ _Colin Barker_, Jun 29 2014 %Y A243985 Cf. A006532, A243917 , A243984. %K A243985 nonn %O A243985 1,2 %A A243985 _Juri-Stepan Gerasimov_, Jun 16 2014 %E A243985 Several terms corrected by _Colin Barker_, Jun 29 2014