A152586 Numbers of the form 13^(2^n) + 2.

15, 171, 28563, 815730723, 665416609183179843, 442779263776840698304313192148785283, 196053476430761073330659760423566015424403280004115787589590963842248963

Offset

1,1

Comments

These numbers are divisible by 3. Expanding the binomial (12+1)^(2^n)+1 we

get 12h+1+2 for some h and 12h+3 is divisible by 3.

Links

Table of n, a(n) for n=1..7.

Formula

a(n) = A176596(n)+2. - R. J. Mathar, Sep 10 2016

Prog

(PARI) g(a, n) = if(a%2, b=2, b=1); for(x=0, n, y=a^(2^x)+b; print1(y", "))

Crossrefs

Sequence in context: A058687 A206594 A354403 * A339547 A082678 A331516

Adjacent sequences: A152583 A152584 A152585 * A152587 A152588 A152589

Keyword

nonn

Author

Cino Hilliard, Dec 08 2008

Status

approved