|
|
A225659
|
|
Primes p where p + sumOfDigits(p) +- 3 is prime.
|
|
1
|
|
|
2, 3, 5, 7, 23, 29, 41, 43, 47, 61, 67, 83, 89, 131, 137, 139, 157, 173, 179, 191, 197, 223, 227, 229, 241, 263, 269, 283, 311, 313, 317, 337, 353, 359, 373, 379, 397, 401, 409, 421, 443, 449, 463, 467, 487, 557
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
EXAMPLE
|
If p = 409, then 409 + sod(409) +- 3 = 409+13 - 3 = 419, which is prime.
If p = 23, then 23 + sod(23) +- 3 = 23+5 + 3 = 31, which is prime.
|
|
MATHEMATICA
|
Select[Prime[Range[102]], Or@@PrimeQ[#+Total[IntegerDigits[#]]+{3, -3}] &] (* Jayanta Basu, May 23 2013 *)
|
|
PROG
|
(PARI)
ok(p)= {my(s=vecsum(digits(p))); isprime(p) && (isprime(p+s-3) || isprime(p+s+3))}
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy,base,dumb
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|