A110949 - OEIS

%I #18 Jan 17 2019 13:44:08

%S 1,2,7,11,191,248,1067,2666,5252,13400,22886,23739,29095

%N Integers n such that 4*10^n + 61 is prime.

%C See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "40061".

%C a(14) > 10^5. - _Robert Price_, Jan 22 2017

%H Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/">List of near-repdigit-related prime numbers</a>.

%H <a href="/index/Pri#Pri_rep">Index entries for primes involving repunits</a>.

%e n = 7 is in the sequence because 4*10^7 + 61 = 4*10000000 + 61 = 40000000 + 61 = 40000061, which is prime.

%o (PARI) isok(n) = isprime(4*10^n+61); \\ _Michel Marcus_, Jan 22 2017

%Y Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054.

%K more,nonn

%O 1,2

%A Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005

%E a(9)-a(11) from _Ray Chandler_, Dec 23 2010

%E Prepended a(1)=1 by _Robert Price_, Jan 22 2017

%E a(12)-a(13) from _Robert Price_, Jan 22 2017