A343566 Numbers k such that A343564(k) is divisible by 2*k.

1, 2, 3, 24, 63, 107, 263, 383, 504, 75414, 17389821, 47574810

Offset: 1

Author

J. M. Bergot and Robert Israel, Apr 20 2021

Keywords

• nonn
• more

Examples

			a(4) = 24 is a term because A343564(24) = 96 is divisible by 2*24 = 48.
		

Crossrefs

Cf. A343564.

Programs

Maple

N:= 100000: # for terms <= N
P:= select(isprime,[seq(i,i=3..2*N)]):
f:= proc(n) local m,Q,q;
  m:= ListTools:-BinaryPlace(P,2*n);
  Q:= convert(P[1..m],set);
  Q:= Q intersect map(t -> 2*n-t, Q);
  add(2*n mod q, q = Q);
end proc:
A343564:= map(f, [$1..N]):
select(t -> A[t] mod (2*t) = 0, [$1..N]);

Extensions

a(11) and a(12) from Martin Ehrenstein, Apr 25 2021