OFFSET
1,1
COMMENTS
By the general conjecture in A235925, this sequence should have infinitely many terms.
LINKS
Zhi-Wei Sun, Table of n, a(n) for n = 1..2000
Z.-W. Sun, Problems on combinatorial properties of primes, arXiv:1402.6641, 2014
EXAMPLE
a(3) = 23 with 23, f(23) = 61, f(61) = 223 and f(223) = 1187 all prime.
MATHEMATICA
f[n_]:=Prime[n]-n+1
p[k_]:=PrimeQ[f[Prime[k]]]&&PrimeQ[f[f[Prime[k]]]]&&PrimeQ[f[f[f[Prime[k]]]]]
n=0; Do[If[p[k], n=n+1; Print[n, " ", Prime[k]]], {k, 1, 10000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Zhi-Wei Sun, Jan 17 2014
STATUS
approved