OFFSET

1,1

COMMENTS

In 1951, A. Ferrier showed that every prime factor of N = (2^148 + 1)/17 is of the form 144396166620968*n + 1, n > 0. He also noted that the first 11 numbers of this form have prime factors under 30 and hence cannot be primes, which implies that N is prime.

REFERENCES

Hans Riesel, Prime numbers and computer methods for factorization, Springer, New York, 2012, pp. 122-123.

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Ferrier's Prime

MATHEMATICA

FactorInteger[#][[1, 1]]&/@(144396166620968*Range[70]+1) (* Harvey P. Dale, Oct 24 2017 *)

PROG

(PARI) for(n=1, 65, print1(factor(144396166620968*n+1)[1, 1], ", "));

(Python)

from sympy import factorint

def A228000(n):

return min(factorint(144396166620968*n + 1)) # Chai Wah Wu, Jul 16 2019

CROSSREFS

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Oct 25 2013

STATUS

approved