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A073805 Numbers k such that 1 + k*R(k) is prime, where R(k) is the reverse of k.

%I A073805 #15 Jul 04 2024 02:39:13
%S A073805 1,2,4,6,10,16,18,20,24,25,26,28,36,42,50,52,58,61,62,63,66,68,70,80,
%T A073805 81,82,85,86,90,100,108,112,116,120,132,136,138,140,152,162,170,190,
%U A073805 198,200,204,205,209,210,211,213,214,219,223,224,228,231,234,236,238
%N A073805 Numbers k such that 1 + k*R(k) is prime, where R(k) is the reverse of k.
%H A073805 Robert Israel, <a href="/A073805/b073805.txt">Table of n, a(n) for n = 1..10000</a>
%e A073805 16 is a term because 16*61 + 1 = 977 is prime.
%p A073805 rev:= proc(n) local L,i;
%p A073805   L:= convert(n,base,10);
%p A073805   add(L[-i]*10^(i-1),i=1..nops(L))
%p A073805 end proc:
%p A073805 filter:= t -> isprime(t*rev(t)+1):
%p A073805 select(filter, [$1..1000]); # _Robert Israel_, Jul 03 2024
%t A073805 Select[Range[250],PrimeQ[# IntegerReverse[#]+1]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Oct 05 2017 *)
%Y A073805 Cf. A004086, A061205.
%K A073805 nonn,easy,base,look
%O A073805 1,2
%A A073805 _Shyam Sunder Gupta_, Aug 23 2002