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Lesser emirps (primes whose digit reversal is a larger prime).
13

%I #17 Sep 08 2021 19:17:03

%S 13,17,37,79,107,113,149,157,167,179,199,337,347,359,389,709,739,769,

%T 1009,1021,1031,1033,1061,1069,1091,1097,1103,1109,1151,1153,1181,

%U 1193,1213,1217,1223,1229,1231,1237,1249,1259,1279,1283,1381,1399,1409,1429

%N Lesser emirps (primes whose digit reversal is a larger prime).

%H R. J. Mathar, <a href="/A109308/b109308.txt">Table of n, a(n) for n = 1..1000</a>

%p read("transforms"):

%p A109308 := proc(n)

%p option remember;

%p local p,R ;

%p if n = 1 then

%p return 13 ;

%p else

%p p := nextprime(procname(n-1)) ;

%p while true do

%p R := digrev(p) ;

%p if R> p and isprime(R) then

%p return p;

%p end if;

%p p := nextprime(p) ;

%p end do:

%p end if;

%p end proc: # _R. J. Mathar_, Oct 12 2012

%t dr[n_]:=FromDigits[Reverse[IntegerDigits[n]]];Select[Prime[Range[1000]], PrimeQ[dr[ # ]]&&dr[ # ]>#&]

%o (PARI) isok(p) = if (isprime(p), my(q=fromdigits(Vecrev(digits(p)))); (p < q) && isprime(q)); \\ _Michel Marcus_, Sep 07 2021

%o (Python)

%o from sympy import isprime, primerange

%o def ok(p): revp = int(str(p)[::-1]); return p < revp and isprime(revp)

%o print(list(filter(ok, primerange(1, 1430)))) # _Michael S. Branicky_, Sep 07 2021

%Y Cf. A006567 (emirps), A109309 (larger emirps).

%K base,nonn

%O 1,1

%A _Zak Seidov_, Jun 25 2005