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A309558
Numbers k such that A001414(k^4+1) is divisible by k.
0
1, 5, 10, 2095, 5623, 13589, 14047, 19519, 21143, 154249
OFFSET
1,2
EXAMPLE
10 is in the sequence because the prime factorization of 10^4+1=10001 is 73*137 and 73+137=210 is divisible by 10.
MAPLE
filter:= proc(n) local F, t, y;
F:= ifactors(n^4+1)[2];
y:= add(t[1]*t[2], t=F);
y mod n = 0
end proc:
select(filter, [$1..200000]);
CROSSREFS
KEYWORD
nonn,more
AUTHOR
J. M. Bergot and Robert Israel, Aug 07 2019
STATUS
approved