cp's OEIS Frontend

A138048 Numbers k such that 15^k + 2 is prime.

%I A138048 #21 Jun 07 2021 01:10:45
%S A138048 0,1,2,4,5,10,11,16,20,52,75,106,112,132,371,3264,3424,5477,7516,
%T A138048 10365,44557,150706
%N A138048 Numbers k such that 15^k + 2 is prime.
%C A138048 No further terms < 100000. - _Ray Chandler_, Aug 05 2011
%C A138048 a(23) > 2*10^5. - _Robert Price_, Jun 23 2015
%H A138048 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=15%5En%2B2&amp;action=Search">PRP Records</a>.
%t A138048 Do[ f = 15^n + 2; If[ PrimeQ[ f ], Print[ {n, f} ] ], {n, 1, 371} ]
%o A138048 (PARI) is(n)=ispseudoprime(15^n+2) \\ _Charles R Greathouse IV_, Feb 17 2017
%Y A138048 Cf. A051783 (k such that 3^k + 2 is prime).
%Y A138048 Cf. A087885 (k such that 5^k + 2 is prime).
%Y A138048 Cf. A090649, A109076, A113480, A138049, A138050, A138051, A087886, A113481.
%K A138048 nonn,more
%O A138048 1,3
%A A138048 _Alexander Adamchuk_, Mar 02 2008
%E A138048 a(16)-a(19) from _Ray Chandler_, Jul 30 2011
%E A138048 a(20) found by Lelio R Paula, Dec 2006
%E A138048 a(21) from _Ray Chandler_, Jul 31 2011
%E A138048 a(22) from _Robert Price_, Jun 23 2015