A328784 Integers k such that the k-th prime divides the k-th Lucas number.

2, 4, 5, 608, 1221, 60264, 205965, 994856, 69709961, 3140421767

Offset

1,1

Links

Table of n, a(n) for n=1..10.

Maple

a:= 1:
b:= 2:
p:= 2:
Res:= NULL:
for n from 2 to 10^6 do
  c:= a+b;
  b:= a;
  a:= c;
  p:= nextprime(p);
  if a mod p = 0 then
    Res:= Res, n;
  fi
od:
Res; # Robert Israel, Oct 30 2019

Prog

(Magma) [n: n in [1..100000] | IsZero(Lucas(n) mod NthPrime(n))];

Crossrefs

Cf. A000032, A000040.

Cf. A075702 (analog with Fibonacci).

Sequence in context: A105288 A242915 A066684 * A128124 A182687 A141062

Adjacent sequences: A328781 A328782 A328783 * A328785 A328786 A328787

Keyword

nonn,more

Author

Juri-Stepan Gerasimov, Oct 30 2019

Extensions

a(8) from Robert Israel, Oct 30 2019

a(9)-a(10) from Daniel Suteu, Nov 07 2019

Status

approved