A081509 Primes of the form 1 + 2^k + 4^k + 6^k.

13, 366993409, 789800591806169089, 8145612997113849913833354347764846494983651329

Offset

1,1

Comments

a(5) has 311 digits. - Harvey P. Dale, Mar 18 2019

Using the above, a(5) = 1 + 2^399 + 4^399 + 6^399. - David A. Corneth, Mar 18 2019

Links

Table of n, a(n) for n=1..4.

Example

n=1: 1 + 2 + 4 + 6 = 13 is prime.

Mathematica

Do[s=1^w+2^w+4^w+6^w; If[IntegerQ[w/100], Print[{w}]]; If[PrimeQ[s], Print[{w, s}]], {w, 0, 1000}]
Select[Table[1+2^n+4^n+6^n, {n, 60}], PrimeQ] (* Harvey P. Dale, Mar 18 2019 *)

Crossrefs

Cf. A081510.

Sequence in context: A158750 A145744 A174309 * A177224 A145234 A334634

Adjacent sequences: A081506 A081507 A081508 * A081510 A081511 A081512

Keyword

nonn

Author

Labos Elemer, Apr 15 2003

Status

approved