login
A372491
Indices k such that A002533(k) is prime.
1
2, 3, 4, 5, 11, 17, 32, 53, 103, 107, 109, 113, 137, 197, 233, 811, 7993, 9281, 14387, 26573, 51361
OFFSET
1,1
COMMENTS
All terms are either primes or powers of 2.
FORMULA
A111011(n) = A002533(a(n)).
EXAMPLE
a(3) = 4 is a term because A002533(4) = 73 is prime.
MAPLE
B[0]:= 1: B[1]:= 1: R:= NULL: count:= 0:
for n from 2 while count < 18 do
B[n]:= 2*B[n-1]+5*B[n-2];
if (isprime(n) or n = 2^padic:-ordp(n, 2)) and isprime(A[n]) then
R:= R, n; count:= count+1
fi
od:
R;
MATHEMATICA
Flatten[Position[LinearRecurrence[{2, 5}, {1, 1}, 1000] , _Integer?PrimeQ]-1] (* James C. McMahon, May 06 2024 *)
CROSSREFS
Sequence in context: A188532 A181288 A255260 * A333610 A052418 A051800
KEYWORD
nonn,more
AUTHOR
Robert Israel, May 03 2024
EXTENSIONS
a(21) from Michael S. Branicky, May 04 2024
STATUS
approved