BBC Russian

A140331

Smallest k such that 3^(3^n) - k is prime.

1, 4, 2, 26, 10, 466, 506, 128, 13342, 5974, 8410, 6470

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

OFFSET

0,2

COMMENTS

This is to 3 as A058220 is to 2.

LINKS

FORMULA

a(n) = A064722(A055777(n)). - Michel Marcus, Jan 28 2015

EXAMPLE

a(4) = 10 because 3^(3^4) - 10 = 443426488243037769948249630619149892793 is prime.

PROG

(PARI) a(n) = x = 3^(3^n); x - precprime(x); \\ Michel Marcus, Jan 28 2015

CROSSREFS

Cf. A055777 (3^(3^n)), A058220.

KEYWORD

more,nonn

AUTHOR

EXTENSIONS

a(5)-a(8) from Cino Hilliard, Jun 02 2008

a(9)-a(10) from Donovan Johnson, Sep 13 2008

a(0) prepended and a(11) from Michael S. Branicky, Aug 23 2024

STATUS

approved