A227948 Zeroless numbers n such that n + (product of digits of n) and n - (product of digits of n) are prime.

21, 23, 27, 29, 81, 83, 253, 293, 299, 343, 347, 349, 431, 437, 439, 471, 473, 477, 529, 623, 653, 659, 677, 743, 893, 1123, 1219, 1253, 1257, 1297, 1423, 1489, 1521, 1523, 1529, 1587, 1589, 1657, 1763, 1853, 1867, 1927, 2151, 2167, 2239, 2277, 2279, 2321, 2327, 2329, 2377, 2413, 2443, 2459, 2467, 2497, 2543, 2569

Offset

1,1

Comments

Intersection of A157676 and A229221 (without the primes containing zero digits).

Links

Table of n, a(n) for n=1..58.

Example

29 - 2*9 = 11 (prime) and 29 + 2*9 = 47 (prime) so 29 is a member of this sequence.
743 - 7*4*3 = 659 (prime) and 743 + 7*4*3 = 827 (prime) so 743 is a member of this sequence.

Prog

(Python)
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(5000) if DP(n) and isprime(n+DP(n)) and isprime(n-DP(n))}
## Simplified by Derek Orr, Apr 05 2015
(PARI) for(n=1, 5000, d=digits(n); p=prod(i=1, #d, d[i]); if(p&&isprime(n+p)&&isprime(n-p), print1(n, ", "))) \\ Derek Orr, Apr 05 2015

Crossrefs

Cf. A157676, A229221, A007954, A052382.

Sequence in context: A329914 A229221 A157676 * A303718 A270108 A335189

Adjacent sequences: A227945 A227946 A227947 * A227949 A227950 A227951

Keyword

nonn,base,easy

Author

Derek Orr, Oct 04 2013

Extensions

More terms from Derek Orr, Apr 05 2015

Status

approved