A077359 Primes whose external digits form a prime. Or primes from which deleting the internal digits leaves a prime.

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

Harvey P. Dale, Table of n, a(n) for n = 1..1000

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

Cf. A069686, A077360.

Sequence in context: A216887 A095320 A238853 * A057448 A049551 A058853

Adjacent sequences: A077356 A077357 A077358 * A077360 A077361 A077362

Keyword

base,nonn

Author

Amarnath Murthy, Nov 05 2002

Extensions

Edited and extended by Klaus Brockhaus, Nov 06 2002

Status

approved