A225659 Primes p where p + sumOfDigits(p) +- 3 is prime.

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

Offset: 1

Author

John-Å. W. Olsen, May 11 2013

Keywords

• nonn
• easy
• base
• dumb

Comments

a(n) = A068690(n), A030144(n), A069556(n), A091727(n), A156756(n) if n<14.

Examples

			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.
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..394

Crossrefs

Cf. A000040, A007605, A068690, A030144, A069556, A091727, A156756.

Programs

Mathematica

Select[Prime[Range[102]],Or@@PrimeQ[#+Total[IntegerDigits[#]]+{3,-3}] &] (* Jayanta Basu, May 23 2013 *)

PARI

ok(p)= {my(s=vecsum(digits(p)));isprime(p) && (isprime(p+s-3) || isprime(p+s+3))}
select(ok,[1..1000]) \\ Andrew Howroyd, Feb 22 2018