A152586 - OEIS

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A152586

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

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

(list; graph; refs; listen; history; text; internal format)

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", "))