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A234695
Primes p with prime(p) - p + 1 also prime.
38
2, 3, 5, 7, 13, 17, 23, 31, 41, 43, 61, 71, 83, 89, 103, 109, 139, 151, 173, 181, 199, 211, 223, 241, 271, 277, 281, 293, 307, 311, 317, 337, 349, 353, 367, 463, 499, 541, 563, 571, 601, 661, 673, 709, 719, 743, 751, 757, 811, 823, 827, 883, 907, 911, 953
OFFSET
1,1
COMMENTS
By the conjecture in A234694, this sequence should have infinitely many terms.
LINKS
FORMULA
a(n) = prime(A234852(n)). - M. F. Hasler, Dec 31 2013
EXAMPLE
a(1) = 2 since prime(2) - 1 = 2 is prime.
a(2) = 3 since prime(3) - 2 = 3 is prime.
a(3) = 5 since prime(5) - 4 = 7 is prime.
a(4) = 7 since prime(7) - 6 = 11 is prime.
MATHEMATICA
n=0; Do[If[PrimeQ[Prime[Prime[k]]-Prime[k]+1], n=n+1; Print[n, " ", Prime[k]]], {k, 1, 1000}]
PROG
(PARI) forprime(p=1, 999, isprime(prime(p)-p+1)&&print1(p", ")) \\ - M. F. Hasler, Dec 31 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Zhi-Wei Sun, Dec 29 2013
STATUS
approved