|
%I #22 Jun 25 2022 11:45:58
%S 3,53,827,3671,5507,8423,8693,30293,42083,42281,42299,53639,57203,
%T 59921,80819,326681,345473,345887,348191,361637,387449,420803,422243,
%U 510299,511019,551339,574181,590813,593171,804653,806363,808991,829601,863729,867131,888011
%N Primes whose reversal + 1 is a square.
%H Robert Israel and K. D. Bajpai, <a href="/A167217/b167217.txt">Table of n, a(n) for n = 1..10000</a> (first 506 entries from K. D. Bajpai)
%e 53 is prime and 35 + 1 = 36 = 6^2.
%e 827 is in the sequence because it is prime and reversal(827) + 1 = 728 + 1 = 729 = 27^2. - _K. D. Bajpai_, Jul 03 2014
%p Nd:= 4: # to get all entries with up to 2*Nd digits
%p revdigs:= proc(x) local F,n,i;
%p F:= convert(x,base,10);
%p n:= nops(F);
%p add(10^(n-i)*F[i],i=1..n);
%p end:
%p Sq:= remove(t -> (t mod 10 = 1), {seq(i^2,i=1..10^Nd-1)}):
%p A:=map(proc(s) local r; r:= revdigs(s-1); if isprime(r) then r else NULL fi end proc, Sq); # _Robert Israel_, Jul 03 2014
%t Select[Prime[Range[10^5]], IntegerQ[Sqrt[FromDigits[Reverse[IntegerDigits[#]]] + 1]] &] (* _K. D. Bajpai_, Jul 03 2014 *)
%K base,nonn
%O 1,1
%A _Claudio Meller_, Oct 30 2009
%E More terms from _K. D. Bajpai_, Jul 03 2014
|
