A155949 Numbers p with property that p and 5 iterations of f(p) all are primes, where f(p)=p^2+p+41.

16355881, 109909799, 156177433, 167667607, 169177649, 196805633, 320142863, 428366489, 610038257, 644062919, 1103804483, 1164167891, 1184418737, 1493813903, 1541169463, 1882406467, 1956211891, 2018075911, 2248153673

Offset

1,1

Comments

Next term a(20)=2493493447.

Links

Table of n, a(n) for n=1..19.

Example

f(n)=n^2+n+41
n=1, p=16355881:
f(p)=267514859642083 prime,
f(f(p))=71564200129323635349724221013, prime
f(f(f(p))) =5121434740149885026514070854977073540325438908499394967223, prime
f(f(f(f(p)))) prime, f(f(f(f(f(p))))) prime, f(f(f(f(f(f(p)))))) not-prime.

Crossrefs

Sequence in context: A204604 A253716 A216004 * A355095 A192203 A248204

Adjacent sequences: A155946 A155947 A155948 * A155950 A155951 A155952

Keyword

nonn

Author

Zak Seidov, Jan 31 2009

Status

approved