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..19
Z.-W. Sun, Problems on combinatorial properties of primes, arXiv:1402.6641, 2014
EXAMPLE
a(3) = 501187 with 501187, f(501187) = 6886357, f(6886357) = 113948711, f(113948711) = 2224096873, f(2224096873) = 50351471977 and f(50351471977) = 1303792228393 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]]]]]&&PrimeQ[f[f[f[f[Prime[k]]]]]]&&PrimeQ[f[f[f[f[f[Prime[k]]]]]]]
n=0; Do[If[p[k], n=n+1; Print[n, " ", Prime[k]]], {k, 1, 10^7}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Zhi-Wei Sun, Jan 17 2014
STATUS
approved