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A077359
Primes whose external digits form a prime. Or primes from which deleting the internal digits leaves a prime.
6
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 223, 229, 233, 239, 263, 269, 283, 293, 307, 311, 317, 331
OFFSET
1,1
LINKS
MATHEMATICA
edpQ[n_]:=Module[{idn=IntegerDigits[n]}, PrimeQ[10idn[[1]]+idn[[-1]]]]; Join[ {2, 3, 5, 7}, Select[Prime[Range[200]], edpQ]] (* Harvey P. Dale, Nov 20 2020 *)
PROG
(PARI) {exdigs(n)=local(a, j, d); d=divrem(n, 10); a=d[2]; n=d[1]; j=1; while(n>10, d=divrem(n, 10); n=d[1]; j=10*j); 10*n+a} forprime(p=1, 335, if(isprime(exdigs(p)), print1(p, ", ")))
CROSSREFS
Sequence in context: A216887 A095320 A238853 * A057448 A049551 A058853
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 05 2002
EXTENSIONS
Edited and extended by Klaus Brockhaus, Nov 06 2002
STATUS
approved