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 A242097 #15 May 27 2018 13:36:27 %S A242097 4,9,94,46,121,961,982,4,526,9,169,6511,5221,9481,1042,6313,4633,1843, %T A242097 1273,94,1405,9235,46,9886,6937,4069,10201,61801,94411,18811,121, %U A242097 44521,96721,52231,65431,42931,67351,52651,92161,48361,961,16171,98671,65971,96781 %N A242097 Sp = reversal of some square s where s = x^2 for x = 1,2,.. (ignoring leading zeros). Sp is in the sequence if it is semiprime. %C A242097 All the terms in sequence are semiprimes (product of two primes) which are reversal of some square, ignoring leading zeros. %H A242097 K. D. Bajpai, <a href="/A242097/b242097.txt">Table of n, a(n) for n = 1..360</a> %e A242097 a(3) = 94 = 2 * 47 which is semiprime. Reversing the digits gives 49 = 7^2. %e A242097 a(4) = 46 = 2 * 23 which is semiprime. Reversing the digits gives 64 = 8^2. %p A242097 with(StringTools): with(numtheory): A242097:= proc() local r; r:= parse(Reverse(convert(x^2,string))); if bigomega(r)=2 then RETURN (r); fi; end: seq(A242097 (), x=1..500); %t A242097 Select[IntegerReverse[Range[200]^2],PrimeOmega[#]==2&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 27 2018 *) %Y A242097 Cf. A001358, A115710, A115711. %K A242097 nonn,base,less %O A242097 1,1 %A A242097 _K. D. Bajpai_, May 04 2014