This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A171807 #12 Mar 23 2025 18:25:54
%S A171807 37,71,157,167,199,907,953,971,991,1151,1193,1213,1223,1231,1237,1279,
%T A171807 1283,1381,1429,1471,1499,1523,1583,1597,1601,1619,1669,1811,1831,
%U A171807 1867,3299,3343,3347,3371,3373,3391,3463,3467,3469,3527,3541,3719,3767,3803
%N A171807 Emirps (A006567) p such that R(prime(p)) is prime.
%F A171807 {n such that n is in A000040 and A006567(n) is in A000040 and A000040(n) is in A000040 and A006567(A000040(n)) is in A000040}.
%e A171807 a(1) = 37 because 37 and R(37) = 73 are prime, as are prime(37) = 157 and R(prime(37)) = 751.
%e A171807 a(2) = 71 because 71 and R(71) = 17 are prime, as are prime(71) = R(prime(71)) = 353 (which is not an emirp because the reversal is the same prime).
%e A171807 a(3) = 157 because 157 and R(157) = 751 are prime, as are prime(157) = R(prime(157)) = 919 (which is not an emirp because the reversal is the same prime).
%e A171807 a(4) = 167 because 167 and R(157) = 671 are prime, as are prime(167) = 991 and R(prime(167)) = 199.
%e A171807 a(5) = 199 because 199 and (199) = 991 are prime, as are prime(199) = 1217 and R(1217)= prime(912) = 7121.
%t A171807 emQ[n_]:=Module[{idn=IntegerDigits[n],revidn},revidn=Reverse[idn];idn!= revidn && PrimeQ[FromDigits[revidn]] && PrimeQ[FromDigits[ Reverse[ IntegerDigits[ Prime[n]]]]]]; Select[Prime[Range[600]],emQ] (* _Harvey P. Dale_, Mar 01 2012 *)
%Y A171807 Cf. A000040, A004086, A006567.
%K A171807 easy,nonn,less,base
%O A171807 1,1
%A A171807 _Jonathan Vos Post_, Dec 18 2009
%E A171807 More terms from _R. J. Mathar_, Jan 25 2010