A085306 - OEIS

%I #12 Feb 13 2021 14:02:42

%S 2,3,11,13,31,101,103,113,211,311,1013,1021,1031,1103,1201,1301,2011,

%T 2111,3001,3011,10103,10111,10211,11003,11113,12011,12101,13001,20011,

%U 20021,20101,20201,21001,21011,21101,22111,30011,100003,100103,101021

%N Prime numbers such that first reversing digits and after squaring equals the result of first-squaring and after-reversing. Primes in A085305.

%H Donovan Johnson, <a href="/A085306/b085306.txt">Table of n, a(n) for n = 1..1000</a>

%F Prime number solutions to rev(x^2) = rev(x)^2.

%e n=13 is here because 31^2 = 961 = rev(169) = rev(13^2) = rev(rev(31)^2).

%e 65 solutions below 1000000.

%t rt[x_] := tn[Reverse[IntegerDigits[x]]] Do[s=rt[n^2]; s1=rt[n]^2; If[Equal[s, s1]&& !Equal[Mod[n, 10], 0]&&PrimeQ[n], Print[n]], {n, 1, 1000000}]

%t (* Second program: *)

%t Select[Prime[Range[10^5]], IntegerReverse[#]^2 == IntegerReverse[#^2]&] (* _Jean-François Alcover_, Feb 13 2021 *)

%Y Cf. A085305.

%K base,nonn

%O 1,1

%A _Labos Elemer_, Jun 27 2003