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Numbers k such that A001414(k^4+1) is divisible by k.
0

%I #5 Aug 07 2019 11:35:45

%S 1,5,10,2095,5623,13589,14047,19519,21143,154249

%N Numbers k such that A001414(k^4+1) is divisible by k.

%e 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.

%p filter:= proc(n) local F, t, y;

%p F:= ifactors(n^4+1)[2];

%p y:= add(t[1]*t[2], t=F);

%p y mod n = 0

%p end proc:

%p select(filter, [$1..200000]);

%Y Cf. A001414, A309534, A309542, A309544.

%K nonn,more

%O 1,2

%A _J. M. Bergot_ and _Robert Israel_, Aug 07 2019