OFFSET
1,1
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
EXAMPLE
743 is prime.
743 - (7*4*3) = 659 is prime.
743 + (7*4*3) = 827 is prime.
So, 743 is a member of this sequence.
MAPLE
MATHEMATICA
id[x_] := IntegerDigits[x]; ti[x_] := Times @@ id[x]; m=5000; Select[Range[3, m, 2], PrimeQ[#] && Min[id[#]] > 0 && PrimeQ[#+ti[#]] && PrimeQ[#-ti[#]]&] (* Zak Seidov, Oct 02 2013 *)
t@n_ := Block[{p = Times @@ IntegerDigits@n},
If[p == 0, {0}, n + {-p, p}]]; Select[Prime@Range@1000,
AllTrue[t@#, PrimeQ] &] (* Hans Rudolf Widmer, Dec 13 2021 *)
PROG
(Python)
import sympy
from sympy import isprime
def DP(n):
p = 1
for i in str(n):
p *= int(i)
return p
{print(n, end=', ') for n in range(10**4) if DP(n) and isprime(n) and isprime(n+DP(n)) and isprime(n-DP(n))}
# Simplified by Derek Orr, Mar 22 2015
(PARI) forprime(p=1, 10^4, d=digits(p); P=prod(i=1, #d, d[i]); if(P&&isprime(p+P)&&isprime(p-P), print1(p, ", "))) \\ Derek Orr, Mar 22 2015
CROSSREFS
KEYWORD
nonn,base,easy,changed
AUTHOR
Derek Orr, Sep 30 2013
STATUS
approved