|
|
A085306
|
|
Prime numbers such that first reversing digits and after squaring equals the result of first-squaring and after-reversing. Primes in A085305.
|
|
3
|
|
|
2, 3, 11, 13, 31, 101, 103, 113, 211, 311, 1013, 1021, 1031, 1103, 1201, 1301, 2011, 2111, 3001, 3011, 10103, 10111, 10211, 11003, 11113, 12011, 12101, 13001, 20011, 20021, 20101, 20201, 21001, 21011, 21101, 22111, 30011, 100003, 100103, 101021
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
Prime number solutions to rev(x^2) = rev(x)^2.
|
|
EXAMPLE
|
n=13 is here because 31^2 = 961 = rev(169) = rev(13^2) = rev(rev(31)^2).
65 solutions below 1000000.
|
|
MATHEMATICA
|
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}]
(* Second program: *)
Select[Prime[Range[10^5]], IntegerReverse[#]^2 == IntegerReverse[#^2]&] (* Jean-François Alcover, Feb 13 2021 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|