A277689 - OEIS

%I #18 Aug 04 2018 11:26:24

%S 13,17,23,37,43,47,53,67,73,83,97,103,107,211,307,311,503,607,811,907,

%T 911,1151,1181,1373,1787,2003,2011,2131,2383,2797,3011,3181,3191,3313,

%U 3373,3727,3797,3919,3929,4003,4007,4373,4787,4919,5003,5011,5101,6007

%N Primes that become palindromic primes when the most significant digit is deleted.

%H Chai Wah Wu, <a href="/A277689/b277689.txt">Table of n, a(n) for n = 1..13189</a> (a(n) for n = 1..1000 from Colin Barker).

%t ppQ[n_]:=Module[{c=FromDigits[Rest[IntegerDigits[n]]]},PrimeQ[c] && PalindromeQ[ c]]; Select[Prime[Range[1000]],ppQ] (* _Harvey P. Dale_, Aug 04 2018 *)

%o (PARI) rotl(a) = my(b, c, d); b=#Str(a); c=floor(a/(10^(b-1))); d=a-c*(10^(b-1)); 10*d+c

%o revint(n) = m=n%10; n\=10; while(n>0, m=m*10+n%10; n\=10); m

%o L=List(); forprime(n=2, 100000, r=rotl(n)\10; if(isprime(r) && revint(r)==r, listput(L, n))); Vec(L)

%Y Cf. A234912, A235000, A277206.

%K nonn,base

%O 1,1

%A _Colin Barker_, Apr 11 2017