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 A287389 #29 May 26 2017 20:56:38
%S A287389 0,3,8,80,99,323,360,575,840,4224,5775,9999,32760,36480,36863,42024,
%T A287389 84680,349280,808200,829920,848240,998000,999999,3055503,3272480,
%U A287389 3426200,3640463,3644280,3682560,5597955,8462280,8803088,30481440,32855823,80622440,99999999
%N A287389 Both k and its reverse are one less than a square.
%C A287389 Contains A028504. - _Robert Israel_, May 25 2017
%C A287389 Except for the first term, the first digit of each term is either 3, 4, 5, 8 or 9. - _Chai Wah Wu_, May 25 2017
%H A287389 Chai Wah Wu, <a href="/A287389/b287389.txt">Table of n, a(n) for n = 1..300</a> (terms n = 1..164 from Robert Israel)
%e A287389 32760 is in the sequence because 32760 = 181^2-1 and its reverse 6723 = 82^2 - 1.
%p A287389 r:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||n):
%p A287389 select(x-> issqr(r(x)+1), [n^2-1$n=1..10000])[]; # _Alois P. Heinz_, May 24 2017
%t A287389 Select[Range[0, 10^6], Function[n, Times @@ Boole@ Map[IntegerQ@ Sqrt@ # &, {n + 1, FromDigits@ Reverse@ IntegerDigits@ n + 1}] == 1]] (* _Michael De Vlieger_, May 24 2017 *)
%o A287389 (PARI) isok(n) = issquare(n+1) && issquare(fromdigits(Vecrev(digits(n)))+1); \\ _Michel Marcus_, May 24 2017
%Y A287389 Cf. A124664: both k and its reverse are one more than a square.
%Y A287389 Cf. A004086, A005563, A028504, A061457, A245361.
%K A287389 nonn,base
%O A287389 1,2
%A A287389 _Bruno Berselli_, May 24 2017