A199302 Palindromic primes in the sense of A007500 with digits '0', '1' and '2' only.

2, 11, 101, 1021, 1201, 110221, 111211, 112111, 120121, 121021, 122011, 1000211, 1010201, 1020101, 1022011, 1022201, 1101211, 1102111, 1102201, 1111021, 1112011, 1120001, 1120121, 1120211, 1121011, 1201021, 1201111, 1210211, 1212121, 1221221, 10002121

Offset

1,1

Comments

All terms except for the initial 2 start and end in the digit 1.

Links

Table of n, a(n) for n=1..31.

Prog

(PARI) allow=Vec("012"); forprime(p=1, default(primelimit), setminus( Set( Vec(Str( p ))), allow)&next; isprime(A004086(p))&print1(p", ")) /* better use the much more efficient code below */
(PARI) a(n=50, list=0, L=[0, 1, 2], needpal=1)={ for(d=1, 1e9, u=vector(d, i, 10^(d-i))~; forvec(v=vector(d, i, [1+(i==1&!L[1]), #L]), isprime(t=vector(d, i, L[v[i]])*u) || next; needpal & !isprime(A004086(t)) & next; list & print1(t", "); n-- || return(t)))}  \\ M. F. Hasler, Nov 06 2011
(Magma) [p: p in PrimesUpTo(10^8) | Set(Intseq(p)) subset [0..2] and IsPrime(Seqint(Reverse(Intseq(p))))];  // Bruno Berselli, Nov 07 2011
(Python)
from itertools import count, islice, product
from sympy import isprime
def A199302_gen(): return (n for n in (int(t+''.join(s)) for l in count(0) for t in '12' for s in product('012', repeat=l)) if isprime(n) and isprime(int(str(n)[::-1])))
A199302_list = list(islice(A199302_gen(), 20)) # Chai Wah Wu, Jan 04 2022

Crossrefs

Cf. A020449 - A020472, A199325 - A199329, A199303 - A199306.

Sequence in context: A114018 A089770 A249447 * A069663 A241100 A337017

Adjacent sequences: A199299 A199300 A199301 * A199303 A199304 A199305

Keyword

nonn,base

Author

M. F. Hasler, Nov 04 2011

Status

approved