

A120378


Integers n such that 2*11^n1 is prime.


5




OFFSET

1,1


COMMENTS

See comments for A057472. Examined in base 12, all n must be even and all primes must be 1primes. For example, 241 is 181 in base 12.
a(9) > 2*10^5.  Robert Price, Nov 06 2015


LINKS

Table of n, a(n) for n=1..8.


FORMULA

a(n) = nth integer k such that 2*11^k1 is prime.


EXAMPLE

a(1)=2 since 2*11^21=241 is the first prime of this form.


MAPLE

for w to 1 do for k from 1 to 2000 do n:=2*11^k1; if isprime(n) then printf("%d, %d", k, n) fi od od;


MATHEMATICA

Select[Range[0, 200000], PrimeQ[2*11^#  1] &] (* Robert Price, Nov 06 2015 *)


CROSSREFS

Cf. A000043, A000668, A002957, A002959, A003307, A079363, A055558.
Sequence in context: A125264 A028985 A067583 * A012345 A012341 A299374
Adjacent sequences: A120375 A120376 A120377 * A120379 A120380 A120381


KEYWORD

more,nonn


AUTHOR

Walter Kehowski, Jun 28 2006


EXTENSIONS

More terms from Ryan Propper, Jan 14 2008
a(7)a(8) from Robert Price, Nov 06 2015


STATUS

approved



