A240678 Primes p such that p*10+k is prime for exactly one value of the digit k.

11, 29, 41, 47, 71, 79, 83, 131, 137, 139, 151, 163, 173, 181, 191, 227, 257, 263, 277, 281, 293, 307, 311, 313, 359, 383, 449, 491, 503, 509, 557, 563, 569, 577, 587, 593, 601, 617, 647, 659, 661, 677, 683, 719, 739, 743, 751, 809, 821, 827, 857, 877, 881

Offset

1,1

Links

Colin Barker, Table of n, a(n) for n = 1..1000

Example

11 is in the sequence because 113 is prime, but 111, 117 and 119 are not prime.

Mathematica

Select[Prime[Range[200]], Total[Boole[PrimeQ[10 #+{1, 3, 7, 9}]]]==1&] (* Harvey P. Dale, Apr 19 2019 *)

Prog

(PARI) forprime(p=2, 1500, t=0; forstep(k=1, 9, 2, if(isprime(p*10+k), t++)); if(t==1, print1(p, ", ")))
(Python)
from sympy import isprime, primerange
def ok(p): return sum(1 for k in [1, 3, 7, 9] if isprime(p*10+k)) == 1
def aupto(limit): return [p for p in primerange(1, limit+1) if ok(p)]
print(aupto(881)) # Michael S. Branicky, Nov 29 2021

Crossrefs

Cf. A067267, A119289, A240679, A240680, A240689.

Sequence in context: A211191 A353043 A350420 * A087693 A106017 A343418

Adjacent sequences: A240675 A240676 A240677 * A240679 A240680 A240681

Keyword

nonn,base

Author

Colin Barker, Apr 10 2014

Status

approved