cp's OEIS Frontend

A049054 Numbers k such that 10^k + 3 is prime.

%I A049054 #60 Mar 01 2022 20:35:02
%S A049054 1,2,5,6,11,17,18,39,56,101,105,107,123,413,426,2607,7668,10470,11021,
%T A049054 17753,26927,60776,98288,300476,509546
%N A049054 Numbers k such that 10^k + 3 is prime.
%C A049054 A102006 is another version of the same sequence. - _N. J. A. Sloane_, Jan 28 2010
%C A049054 Verified existing 21 terms. If another term exists, it is > 39456. - _Robert Price_, Aug 16 2010
%H A049054 Makoto Kamada, <a href="https://stdkmd.net/nrr/1/10003.htm#prime">Prime numbers of the form 100...003</a>.
%H A049054 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=10%5En%2B3">PRP Records.</a>
%H A049054 Sabin Tabirca and Kieran Reynolds, <a href="http://multimedia.ucc.ie/Staff/ST/articles/SNJ03_Tabirca1.ps">Lacunary Prime Numbers</a>.
%F A049054 a(n) = A102006(n) + 1.
%e A049054 5 is a term since 10^5 + 3 = 100003 is a prime.
%e A049054 6 is a term since 10^6 + 3 = 1000003 is a prime.
%t A049054 Do[ If[ PrimeQ[ 10^n + 3], Print[n]], {n, 0, 18000}] (* _Robert G. Wilson v_ Jun 15 2002 *)
%o A049054 (PARI) is(n)=isprime(10^n + 3) \\ _Charles R Greathouse IV_, Apr 28 2015
%Y A049054 Cf. A102006, A159352.
%K A049054 hard,more,nonn
%O A049054 1,2
%A A049054 _G. L. Honaker, Jr._
%E A049054 More terms from _Robert G. Wilson v_, Jun 15 2002
%E A049054 a(16) from _Ray Chandler_, Oct 09 2003
%E A049054 a(17)-a(20) from _Robert G. Wilson v_, Jan 18 2005
%E A049054 a(21) from _Jason Earls_, Jan 01 2008
%E A049054 a(22) from _Robert Price_, Jan 09 2011
%E A049054 a(23) from _Robert Price_, Mar 03 2011
%E A049054 a(24) from _Edward A. Trice_, Oct 21 2012
%E A049054 a(25) from _Paul Bourdelais_, Jan 28 2021