cp's OEIS Frontend

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.

A225739 Palindromic squares whose sum of digits is also a palindromic square.

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%I A225739 #18 May 14 2013 21:14:52
%S A225739 1,4,9,121,10201,12321,1002001,100020001,102030201,10000200001,
%T A225739 1000002000001,1002003002001,100000020000001,10000000200000001,
%U A225739 10002000300020001,1000000002000000001,100000000020000000001,100002000030000200001
%N A225739 Palindromic squares whose sum of digits is also a palindromic square.
%C A225739 Are there finitely many terms not of the form (10^n+1)^2 or (100^n+10^n+1)^2? I haven't found any. - _Charles R Greathouse IV_, May 14 2013
%F A225739 a(n) < 32^n. - _Charles R Greathouse IV_, May 14 2013
%e A225739 12321 is included because it is a palindromic square and 1+2+3+2+1=9 is also a palindromic square.
%e A225739 5265533355625 is not included because although it is a palindromic square its sum of digits, 55, is not.
%t A225739 id[n_]:=IntegerDigits[n]; palQ[n_]:=Reverse[id[n]]==id[n]; t={}; Do[If[palQ[x=n^2] && palQ[y=Total[id[x]]] && IntegerQ[Sqrt[y]], AppendTo[t,x]],{n,1.2*10^6}]; t
%o A225739 (PARI) ispal(n)=my(v=digits(n));for(i=1,#v\2,if(v[i]!=v[#v+1-i],return(0)));1
%o A225739 for(n=1,1e6,s=sumdigits(n^2); issquare(s) && ispal(s) && ispal(n^2) && print1(n^2", ")) \\ _Charles R Greathouse IV_, May 14 2013
%Y A225739 Subsequence of A002779.
%K A225739 nonn,base
%O A225739 1,2
%A A225739 _Jayanta Basu_, May 14 2013
%E A225739 a(13)-a(18) from _Charles R Greathouse IV_, May 14 2013