A309248 Primes p such that p * (sum of digits of p) - 2 is prime.

2, 3, 5, 7, 23, 29, 83, 89, 113, 131, 157, 173, 179, 191, 197, 199, 223, 281, 283, 311, 353, 359, 397, 401, 443, 467, 557, 593, 797, 809, 821, 827, 829, 863, 887, 977, 997, 1031, 1033, 1093, 1109, 1163, 1187, 1259, 1361, 1433, 1451, 1471, 1549, 1637, 1657, 1699

Offset

1,1

Links

Hauke Löffler, Table of n, a(n) for n = 1..10000

Example

2 is in the sequence because 2*(2)-2 = 2 prime.
23 is in the sequence because 23*(2+3)-2 = 113 prime.

Prog

(SageMath)
def isA309248(p):
    s = sum(p.digits())
    return is_prime(p * s - 2)
[p for p in prime_range(1000) if isA309248(p)]

Crossrefs

Cf. A000040, A309249.

Sequence in context: A210110 A235144 A235126 * A267014 A113611 A038925

Adjacent sequences: A309245 A309246 A309247 * A309249 A309250 A309251

Keyword

nonn,base

Author

Hauke Löffler, Jul 18 2019

Status

approved