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A245744
Primes p such that p + d is also prime, where d is the smallest nonzero digit of p.
6
29, 67, 89, 227, 239, 269, 457, 487, 499, 607, 677, 827, 2027, 2087, 2237, 2267, 2309, 2339, 2549, 2657, 2687, 2729, 2789, 2969, 2999, 3257, 3299, 3329, 3527, 3929, 4229, 4259, 4447, 4789, 4969, 4999, 5279, 5479, 5647, 6067, 6269, 6299, 6469, 6547, 6827
OFFSET
1,1
COMMENTS
The least significant digit of a(n) is either 7 or 9. - Colin Barker, Aug 03 2014
The smallest nonzero digit of a(n) is 2, 4, 6 or 8. - Colin Barker, Aug 04 2014
LINKS
EXAMPLE
607 is in the sequence because 607 + 6 = 613, which is prime.
PROG
(PARI) select(p->v=vecsort(digits(p), , 8); isprime(p+v[1+!v[1]]), primes(2000))
(Magma) [p: p in PrimesUpTo(7000) | IsPrime(p+d) where d is [i: i in Set(Intseq(p)) | not IsZero(i)][1]]; // Bruno Berselli, Jul 31 2014
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Colin Barker, Jul 31 2014
STATUS
approved