A317887 Numbers k such that 4^k - 3^k + 2^k is prime.

1, 2, 4, 18, 56, 60, 88, 1288, 1784, 3406, 9250, 11968, 36216, 57206

Offset

1,2

Comments

1 is the only odd number in this sequence.

a(15) > 65432.

Links

Table of n, a(n) for n=1..14.

Example

4^2 - 3^2 + 2^2 = 16 - 9 + 4 = 11 is prime.

Mathematica

Select[Range[0, 5000], PrimeQ[4^# - 3^# + 2^#] &]

Prog

(PARI) for(n=1, 5000, if(ispseudoprime(4^n-3^n+2^n), print1(n, ", ")))

Crossrefs

Cf. A083324, A138699.

Sequence in context: A318249 A093045 A330432 * A083694 A179040 A241685

Adjacent sequences: A317884 A317885 A317886 * A317888 A317889 A317890

Keyword

nonn,more

Author

Jinyuan Wang, Aug 09 2018

Extensions

a(13)-a(14) from Giovanni Resta, Aug 10 2018

Status

approved