A240843 Primes p with property that appending or prepending any single decimal digit to p does not produce a prime.

773, 1103, 1301, 3947, 3989, 4241, 4637, 4931, 5039, 5387, 5417, 6803, 6917, 6971, 7229, 7451, 7703, 7753, 10211, 10303, 10337, 10607, 10657, 10723, 10859, 11117, 11399, 11423, 11489, 11717, 11813, 11971, 11987, 12119, 12329, 12541, 12653, 12659, 12907, 12983

Offset

1,1

Links

Table of n, a(n) for n=1..40.

Formula

A119289 INTERSECT A155762.

Example

1103 belongs to this sequence because 10*1103 + k and k*10^4 + 1103, for k = 1 to 9, are all composite.

Mathematica

fQ[n_] := Block[{e = Floor[ Log10@ n] + 1, r = Range@ 9}, Union@ Flatten[ PrimeQ[{10 n + r, r*10^e + n}]] == {False}]; Select[ Prime@ Range@ 1550, fQ] (* Robert G. Wilson v, Apr 15 2014 *)

Prog

(PARI) for(n=2, 12983, v=n; if(isprime(n), s=#Str(v); t=0; for(k=1, 9, if(isprime(10*v+k)||isprime(k*10^s+v), break, t++)); if(t==9, print1(v, ", "))); n=v);

Crossrefs

Subsequence of A119289 and of A155762.

Sequence in context: A233647 A285755 A264255 * A133963 A133964 A033919

Adjacent sequences: A240840 A240841 A240842 * A240844 A240845 A240846

Keyword

nonn,base

Author

Arkadiusz Wesolowski, Apr 13 2014

Status

approved