OFFSET
1,1
COMMENTS
To see if some m is a term we don't have to factor m^4 + 1 entirely. All we need to know is if the largest prime factor is less than k = m^4 + 1. - David A. Corneth, Jul 31 2020
LINKS
David A. Corneth, Table of n, a(n) for n = 1..7762 (first 1000 terms from Robert Israel)
EXAMPLE
1600 is a member because 1600^4+1=17^2*113*337*641*929 has all its prime divisors < 1600.
MAPLE
filter := proc(n) max(numtheory:-factorset(n^4 + 1)) < n; end proc:
select(filter, [$1..40000]);
MATHEMATICA
filterQ[k_] := FactorInteger[k^4 + 1][[-1, 1]] < k;
Select[Range[40000], filterQ] (* Jean-François Alcover, Jul 31 2020 *)
PROG
(Magma) [k: k in [1..31000]| Max(PrimeDivisors(k^4+1)) lt k]; // Marius A. Burtea, Aug 07 2019
(PARI) is(n) = my(f = factor(n^4 + 1, n + 1)); f[#f~, 1] < n \\ David A. Corneth, Jul 31 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Aug 07 2019
STATUS
approved